diff --git a/mamweb/templates/april.html b/mamweb/templates/april.html
index 92266311..bb24d9d4 100644
--- a/mamweb/templates/april.html
+++ b/mamweb/templates/april.html
@@ -59,3 +59,22 @@
     walkText(document.body);
   </script>
 {% endif %}
+
+
+
+{% if april == 2024 %}
+  <script>
+    {#  By https://stackoverflow.com/a/34559316 #}
+    function walkText(node) {
+      if (node.nodeType == 3) {
+        node.data = node.data.replace(/M&M/g, "W8W");
+      }
+      if (node.nodeType == 1 && node.nodeName != "SCRIPT") {
+        for (var i = 0; i < node.childNodes.length; i++) {
+          walkText(node.childNodes[i]);
+        }
+      }
+    }
+    walkText(document.body);
+  </script>
+{% endif %}
diff --git a/mamweb/templates/base.html b/mamweb/templates/base.html
index 8294d2b8..4a21c43c 100644
--- a/mamweb/templates/base.html
+++ b/mamweb/templates/base.html
@@ -121,6 +121,6 @@
 
     <script src="{% static 'bootstrap/js/bootstrap.bundle.js' %}"></script>
     {% include 'april.html' %}
-	{% block js %}{% endblock %}
+  	{% block js %}{% endblock %}
   </body>
 </html>
diff --git a/seminar/views/views_all.py b/seminar/views/views_all.py
index 318eee21..662c5025 100644
--- a/seminar/views/views_all.py
+++ b/seminar/views/views_all.py
@@ -8,6 +8,7 @@ from django.http import Http404
 from django.db.models import Q, Sum, Count
 from django.views.generic.base import RedirectView
 from django.core.exceptions import PermissionDenied
+from django.contrib.staticfiles.finders import find
 
 import seminar.models as s
 import seminar.models as m
@@ -36,6 +37,7 @@ import unicodedata
 import logging
 import time
 from collections.abc import Sequence
+import http
 
 from seminar.utils import aktivniResitele
 
@@ -562,17 +564,25 @@ def cisloObalkyView(request, rocnik, cislo):
 
 
 def obalkyView(request, resitele):
+	if len(resitele) == 0:
+		return HttpResponse(
+			render(request, 'universal.html', {
+				'title': 'Není pro koho vyrobit obálky.',
+				'text': 'Právě ses pokusil/a vygenerovat obálky pro prázdnou množinu lidí. Můžeš to zkusit změnit, případně se zeptej webařů :-)',
+				}),
+			status=http.HTTPStatus.NOT_FOUND,
+			)
+
 	tex = render(request,'seminar/archiv/obalky.tex', {'resitele': resitele}).content
 
-	tempdir = tempfile.mkdtemp()
-	with open(tempdir+"/obalky.tex","w") as texfile:
-		texfile.write(tex.decode())
-	shutil.copy(os.path.join(settings.STATIC_ROOT, 'seminar/lisak.pdf'), tempdir)
-	subprocess.call(["pdflatex","obalky.tex"], cwd = tempdir)
+	with tempfile.TemporaryDirectory() as tempdir:
+		with open(tempdir+"/obalky.tex","w") as texfile:
+			texfile.write(tex.decode())
+		shutil.copy(find('seminar/lisak.pdf'), tempdir)
+		subprocess.call(["pdflatex","obalky.tex"], cwd = tempdir)
 
-	with open(tempdir+"/obalky.pdf","rb") as pdffile:
-		response = HttpResponse(pdffile.read(), content_type='application/pdf')
-	shutil.rmtree(tempdir)
+		with open(tempdir+"/obalky.pdf","rb") as pdffile:
+			response = HttpResponse(pdffile.read(), content_type='application/pdf')
 	return response
 
 
diff --git a/sifrovacka/admin.py b/sifrovacka/admin.py
index 71d191d4..5099c241 100644
--- a/sifrovacka/admin.py
+++ b/sifrovacka/admin.py
@@ -1,8 +1,10 @@
 from django.contrib import admin
 
-from .models import OdpovedUcastnika, SpravnaOdpoved
+from .models import OdpovedUcastnika, SpravnaOdpoved, NapovezenoUcastnikovi, Napoveda
 
 # Register your models here.
 
 admin.site.register(OdpovedUcastnika)
 admin.site.register(SpravnaOdpoved)
+admin.site.register(Napoveda)
+admin.site.register(NapovezenoUcastnikovi)
diff --git a/sifrovacka/forms.py b/sifrovacka/forms.py
index e3eba7c7..3ae75cc1 100644
--- a/sifrovacka/forms.py
+++ b/sifrovacka/forms.py
@@ -1,6 +1,6 @@
 from django.core.exceptions import ValidationError
 from django.forms import ModelForm, Textarea
-from .models import OdpovedUcastnika, SpravnaOdpoved
+from .models import OdpovedUcastnika, SpravnaOdpoved, NapovezenoUcastnikovi, Napoveda
 
 
 class SifrovackaForm(ModelForm):
@@ -16,3 +16,15 @@ class SifrovackaForm(ModelForm):
 		if SpravnaOdpoved.objects.filter(sifra=sifra).count() == 0:
 			raise ValidationError("Tohle číslo šifry v databázi nemáme. Zkontrolujte si ho prosím.")
 		return sifra
+
+
+class NapovedaForm(ModelForm):
+	class Meta:
+		model = NapovezenoUcastnikovi
+		fields = ["sifra",]
+
+	def clean_sifra(self):
+		sifra = self.cleaned_data.get('sifra')
+		if Napoveda.objects.filter(sifra=sifra).count() == 0:
+			raise ValidationError("K tomuto číslu šifry nemáme nápovědu. Zkontrolujte si ho prosím.")
+		return sifra
diff --git a/sifrovacka/migrations/0004_napoveda_napovezenoucastnikovi.py b/sifrovacka/migrations/0004_napoveda_napovezenoucastnikovi.py
new file mode 100644
index 00000000..cba7ae8f
--- /dev/null
+++ b/sifrovacka/migrations/0004_napoveda_napovezenoucastnikovi.py
@@ -0,0 +1,65 @@
+# Generated by Django 4.2.8 on 2024-04-14 12:57
+
+from django.db import migrations, models
+import django.db.models.deletion
+import django.utils.timezone
+
+
+class Migration(migrations.Migration):
+    dependencies = [
+        (
+            "seminar",
+            "0114_related_name_se_zmenilo_a_django_chce_migraci_tak_dostane_migraci",
+        ),
+        ("sifrovacka", "0003_odpoveducastnika_uspech"),
+    ]
+
+    operations = [
+        migrations.CreateModel(
+            name="Napoveda",
+            fields=[
+                (
+                    "id",
+                    models.AutoField(
+                        auto_created=True,
+                        primary_key=True,
+                        serialize=False,
+                        verbose_name="ID",
+                    ),
+                ),
+                ("text", models.TextField()),
+                ("sifra", models.IntegerField()),
+            ],
+        ),
+        migrations.CreateModel(
+            name="NapovezenoUcastnikovi",
+            fields=[
+                (
+                    "id",
+                    models.AutoField(
+                        auto_created=True,
+                        primary_key=True,
+                        serialize=False,
+                        verbose_name="ID",
+                    ),
+                ),
+                ("sifra", models.IntegerField(verbose_name="Číslo šifry")),
+                (
+                    "timestamp",
+                    models.DateTimeField(
+                        default=django.utils.timezone.now, verbose_name="Timestamp"
+                    ),
+                ),
+                (
+                    "resitel",
+                    models.ForeignKey(
+                        on_delete=django.db.models.deletion.CASCADE,
+                        to="seminar.resitel",
+                    ),
+                ),
+            ],
+            options={
+                "ordering": ["-timestamp"],
+            },
+        ),
+    ]
diff --git a/sifrovacka/models.py b/sifrovacka/models.py
index 6517c2e0..beabd0a7 100644
--- a/sifrovacka/models.py
+++ b/sifrovacka/models.py
@@ -25,3 +25,20 @@ class SpravnaOdpoved(models.Model):
 
 	def __str__(self):
 		return f"{self.sifra}: {self.odpoved}"
+
+
+class NapovezenoUcastnikovi(models.Model):
+	class Meta:
+		ordering = ["-timestamp"]
+
+	resitel = models.ForeignKey(Resitel, blank=False, null=False, on_delete=models.CASCADE)
+	sifra = models.IntegerField("Číslo šifry", blank=False, null=False,)
+	timestamp = models.DateTimeField("Timestamp", blank=False, null=False, default=timezone.now)
+
+
+class Napoveda(models.Model):
+	text = models.TextField(blank=False, null=False,)
+	sifra = models.IntegerField(blank=False, null=False,)
+
+	def __str__(self):
+		return f"{self.sifra}: {self.text}"
diff --git a/sifrovacka/templates/sifrovacka/napoveda.html b/sifrovacka/templates/sifrovacka/napoveda.html
new file mode 100644
index 00000000..cce48ed8
--- /dev/null
+++ b/sifrovacka/templates/sifrovacka/napoveda.html
@@ -0,0 +1,50 @@
+{% extends "base.html" %}
+
+{% block content %}
+
+  <br>
+
+  <h1>{% block nadpis1a %}M&Mí šifrovačka{% endblock nadpis1a %}</h1>
+
+  <br>
+
+  <h2>Získat nápovědu k šifře:</h2>
+
+  <form action="{% url 'sifrovacka_napoveda' %}" method="post">
+    <table class="form">
+      {{form.non_field_errors}}
+      {% for field in form %}
+        <tr>
+          <td>
+            <label class="field-label{% if field.field.required %} field-required{% endif %}" for="{{ field.id_for_label }}">
+              {{ field.label }}
+            </label>
+
+          </td>
+
+          <td {% if field.help_text %} class="field-with-comment"{% endif %}>
+            {{ field }}
+            <span class="field-comment">{{ field.help_text|safe }}</span>
+          </td>
+
+        </tr>
+
+
+        {% if field.errors %}
+          <tr>
+            <td colspan="2"><span class="field-error">{{ field.errors }}</span></td>
+          </tr>
+        {% endif %}
+      {% endfor %}
+    </table>
+
+    {% csrf_token %}
+
+    <input type="submit" value="Chci nápovědu">
+  </form>
+
+  <p><a href="{% url 'sifrovacka' %}">Nechceme nápovědu, známe řešení!</a></p>
+
+  <p><a href="{% url 'sifrovacka_preskoceni' %}">Přeskoč šifru</a></p>
+
+{% endblock content %}
diff --git a/sifrovacka/templates/sifrovacka/napovedy_list.html b/sifrovacka/templates/sifrovacka/napovedy_list.html
new file mode 100644
index 00000000..dc729947
--- /dev/null
+++ b/sifrovacka/templates/sifrovacka/napovedy_list.html
@@ -0,0 +1,23 @@
+{% extends "base.html" %}
+
+{% block content %}
+
+  <h1>{% block nadpis1a %}Šifrovačka vzaté nápovědy{% endblock nadpis1a %}</h1>
+
+  <table class="dosla_reseni">
+    <tr>
+      <th>Timestamp</th>
+      <th>Řešitel</th>
+      <th>Šifra</th>
+    </tr>
+
+    {% for u in object_list %}
+      <tr>
+        <td>{{ u.timestamp }}</td>
+        <td>{{ u.resitel }}</td>
+        <td>{{ u.sifra }}</td>
+      </tr>
+    {% endfor %}
+  </table>
+
+{% endblock content %}
diff --git a/sifrovacka/templates/sifrovacka/preskoceni.html b/sifrovacka/templates/sifrovacka/preskoceni.html
new file mode 100644
index 00000000..64e777ea
--- /dev/null
+++ b/sifrovacka/templates/sifrovacka/preskoceni.html
@@ -0,0 +1,54 @@
+{% extends "base.html" %}
+
+{% block content %}
+
+  <br>
+
+  <h1>{% block nadpis1a %}M&Mí šifrovačka{% endblock nadpis1a %}</h1>
+
+  <br>
+
+  <h2>Přeskočit šifru:</h2>
+
+  <form action="{% url 'sifrovacka_preskoceni' %}" method="post">
+    <table class="form">
+      {{form.non_field_errors}}
+      {% for field in form %}
+        {% if field.id_for_label != "id_odpoved" %}
+          <tr>
+            <td>
+              <label class="field-label{% if field.field.required %} field-required{% endif %}" for="{{ field.id_for_label }}">
+                {{ field.label }}
+              </label>
+
+            </td>
+
+            <td {% if field.help_text %} class="field-with-comment"{% endif %}>
+              {{ field }}
+              <span class="field-comment">{{ field.help_text|safe }}</span>
+            </td>
+
+          </tr>
+
+
+          {% if field.errors %}
+            <tr>
+              <td colspan="2"><span class="field-error">{{ field.errors }}</span></td>
+            </tr>
+          {% endif %}
+        {% else %}
+          {{ field.as_hidden }}
+        {% endif %}
+      {% endfor %}
+    </table>
+
+    {% csrf_token %}
+
+    <input type="submit" value="Chceme další stanoviště bez vyřešení šifry">
+  </form>
+
+  <p><a href="{% url 'sifrovacka' %}">Nechceme přeskočit, známe řešení!</a></p>
+
+  <p><a href="{% url 'sifrovacka_napoveda' %}">Nechceme přeskakovat, ale nápověda by se šikla.</a></p>
+
+{% endblock content %}
diff --git a/sifrovacka/templates/sifrovacka/sifrovacka.html b/sifrovacka/templates/sifrovacka/sifrovacka.html
index 4e0cc15a..1ce95454 100644
--- a/sifrovacka/templates/sifrovacka/sifrovacka.html
+++ b/sifrovacka/templates/sifrovacka/sifrovacka.html
@@ -43,4 +43,8 @@
     <input type="submit" value="Tak pravím!">
   </form>
 
+  <p><a href="{% url 'sifrovacka_napoveda' %}">Získat nápovědu</a></p>
+
+  <p><a href="{% url 'sifrovacka_preskoceni' %}">Přeskoč šifru</a></p>
+
 {% endblock content %}
diff --git a/sifrovacka/urls.py b/sifrovacka/urls.py
index a7af5e54..85f9c4cc 100644
--- a/sifrovacka/urls.py
+++ b/sifrovacka/urls.py
@@ -1,7 +1,7 @@
 from django.urls import path
 
 from seminar.utils import org_required, resitel_or_org_required
-from .views import SifrovackaView, SifrovackaListView
+from .views import SifrovackaView, SifrovackaListView, NapovedaView, NapovedaListView, PreskoceniView
 
 urlpatterns = [
 	path(
@@ -14,4 +14,19 @@ urlpatterns = [
 		org_required(SifrovackaListView.as_view()),
 		name='sifrovacka_odpovedi'
 	),
+	path(
+		'napoveda/',
+		resitel_or_org_required(NapovedaView.as_view()),
+		name='sifrovacka_napoveda'
+	),
+	path(
+		'napovedy/',
+		org_required(NapovedaListView.as_view()),
+		name='sifrovacka_napovedy'
+	),
+	path(
+		'preskoceni/',
+		resitel_or_org_required(PreskoceniView.as_view()),
+		name='sifrovacka_preskoceni'
+	),
 ]
diff --git a/sifrovacka/views.py b/sifrovacka/views.py
index 9c4af3ed..59f3deec 100644
--- a/sifrovacka/views.py
+++ b/sifrovacka/views.py
@@ -2,8 +2,8 @@ from django.urls import reverse
 from django.views.generic import FormView, ListView
 
 from seminar.views import formularOKView
-from .forms import SifrovackaForm
-from .models import OdpovedUcastnika, SpravnaOdpoved
+from .forms import SifrovackaForm, NapovedaForm
+from .models import OdpovedUcastnika, SpravnaOdpoved, Napoveda, NapovezenoUcastnikovi
 from seminar.models.personalni import Resitel
 
 
@@ -24,10 +24,47 @@ class SifrovackaView(FormView):
 
 		instance.uspech = True
 		instance.save()
-		
+
 		return formularOKView(self.request, f'<h1>{sifra.skryty_text}</h1> <p><a href="{reverse("sifrovacka")}">Odevzdat další.</a></p><br><br><br>')
 
 
 class SifrovackaListView(ListView):
 	template_name = 'sifrovacka/odpovedi_list.html'
 	model = OdpovedUcastnika
+
+
+class NapovedaView(FormView):
+	template_name = 'sifrovacka/napoveda.html'
+	form_class = NapovedaForm
+
+	def form_valid(self, form):
+		instance = form.save(commit=False)
+		resitel = Resitel.objects.get(osoba__user=self.request.user)
+		instance.resitel = resitel
+
+		if NapovezenoUcastnikovi.objects.filter(resitel=resitel, sifra=instance.sifra).first() is None:
+			instance.save()
+
+		napoveda = Napoveda.objects.filter(sifra=instance.sifra).first()
+		return formularOKView(self.request, f'<h1>Nápověda k šifře číslo {instance.sifra} je:</h1><p>{napoveda.text}</p> <p><a href="{reverse("sifrovacka")}">Odevzdat řešení.</a></p><br><br><br>')
+
+
+class NapovedaListView(ListView):
+	template_name = 'sifrovacka/napovedy_list.html'
+	model = NapovezenoUcastnikovi
+
+
+class PreskoceniView(FormView):
+	template_name = 'sifrovacka/preskoceni.html'
+	form_class = SifrovackaForm
+	initial = {"odpoved": "=======PŘESKOČENO======="}
+
+	def form_valid(self, form):
+		instance = form.save(commit=False)
+		instance.odpoved = "=======PŘESKOČENO======="
+		resitel = Resitel.objects.get(osoba__user=self.request.user)
+		instance.resitel = resitel
+		instance.save()
+		sifra = SpravnaOdpoved.objects.filter(sifra=instance.sifra).first()  # FIXME co když je více "správných" odpovědí?
+
+		return formularOKView(self.request, f'<h1>{sifra.skryty_text}</h1> <p><a href="{reverse("sifrovacka")}">Zpět na odevzdávátko.</a></p><br><br><br>')
diff --git a/soustredeni/views.py b/soustredeni/views.py
index f2aafdf7..f150b6b8 100644
--- a/soustredeni/views.py
+++ b/soustredeni/views.py
@@ -9,6 +9,7 @@ import tempfile
 import shutil
 import subprocess
 from pathlib import Path
+import http
 
 from seminar.views import obalkyView
 
@@ -76,17 +77,25 @@ def soustredeniUcastniciExportView(request, soustredeni):
 def soustredeniStvrzenkyView(request, soustredeni):
 	soustredeni = get_object_or_404(Soustredeni, id=soustredeni)
 	ucastnici = Resitel.objects.filter(soustredeni=soustredeni)
+	if ucastnici.count() == 0:
+		return HttpResponse(
+			render(request, 'universal.html', {
+				'title': 'Není pro koho vyrobit stvrzenky.',
+				'text': 'Právě ses pokusil/a vygenerovat stvrzenky pro prázdnou množinu lidí. Můžeš to zkusit změnit, případně se zeptej webařů :-)',
+				}),
+			status=http.HTTPStatus.NOT_FOUND,
+			)
 	castka = Nastaveni.get_solo().cena_sous
 	tex = render(request, 'soustredeni/stvrzenky.tex', {'ucastnici': ucastnici, 'soustredeni': soustredeni, 'castka': castka}).content
 
-	tempdir = Path(tempfile.mkdtemp())
-	with open(tempdir / "stvrzenky.tex", "w") as texfile:
-		texfile.write(tex.decode())
+	with tempfile.TemporaryDirectory() as tempdirfn:
+		tempdir = Path(tempdirfn)
+		with open(tempdir / "stvrzenky.tex", "w") as texfile:
+			texfile.write(tex.decode())
 
-	shutil.copy(find('images/logomm.pdf'), tempdir)
-	subprocess.call(["pdflatex", "stvrzenky.tex"], cwd = tempdir, stdout=subprocess.DEVNULL)
+		shutil.copy(find('images/logomm.pdf'), tempdir)
+		subprocess.call(["pdflatex", "stvrzenky.tex"], cwd = tempdir, stdout=subprocess.DEVNULL)
 
-	with open(tempdir / "stvrzenky.pdf", "rb") as pdffile:
-		response = HttpResponse(pdffile.read(), content_type='application/pdf')
-	shutil.rmtree(tempdir)
+		with open(tempdir / "stvrzenky.pdf", "rb") as pdffile:
+			response = HttpResponse(pdffile.read(), content_type='application/pdf')
 	return response