diff --git a/.gitignore b/.gitignore
index af8292d..fabf8d6 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1,5 +1,5 @@
 # Calendar files
-calendar.ics
+cal.ics
 # Config file
 config.yml
 
diff --git a/config.example.yml b/config.example.yml
index 6a750de..26620f9 100644
--- a/config.example.yml
+++ b/config.example.yml
@@ -4,94 +4,95 @@
 
 # List of subjects
 subjects:
-  - name: Gym
-    id: gym
+  gym:
+    name: Gym
 
-  - name: Maths
-    id: mat
+  mat:
+    name: Maths
 
-  - name: French
-    id: fr
+  fr:
+    name: French
 
-  - name: Chemistry
-    id: chem
+  chem:
+    name: Chemistry
 
-  - name: Physics
-    id: phys
+  phys:
+    name: Physics
 
-  - name: Contemporary world
-    id: world
+  world:
+    name: Contemporary world
 
-  - name: Info
-    id: info
+  info:
+    name: Info
 
-  - name: Drama
-    id: dram
+  dram:
+    name: drama
 
-  - name: ECR
-    id: ecr
+  ecr:
+    name: ECR
 
-  - name: English
-    id: en
+  en:
+    name: English
 
-  - name: Music
-    id: mus
+  mus:
+    name: Music
 
 # the cycle is postponed on these days
+# make sure to format dates exactly like this (otherwise it won't be parsed as a date!)
 vacation_days:
-  - single: 2023-9-4
+  - single: 2023-09-04
 
-  - single: 2023-10-9
+  - single: 2023-10-09
 
   - start:  2023-10-30
-    end:    2023-11-3
+    end:    2023-11-03
 
   - single: 2023-11-17
 
   - single: 2023-11-24
 
   - start:  2023-12-25
-    end:    2024-1-8
+    end:    2024-01-08
 
-  - start:  2024-1-29
-    end:    2024-2-5
+  - start:  2024-01-29
+    end:    2024-02-05
 
-  - start:  2024-3-1
-    end:    2024-3-10
+  - start:  2024-03-01
+    end:    2024-03-10
 
-  - start:  2024-3-29
-    end:    2024-4-5
+  - start:  2024-03-29
+    end:    2024-04-05
 
-  - single: 2024-4-19
+  - single: 2024-04-19
 
-  - start:  2024-5-17
-    end:    2024-5-20
+  - start:  2024-05-17
+    end:    2024-05-21
 
-start_date: 2023-8-24
-end_date:   2024-6-20
+start_date: 2023-08-25
+end_date:   2024-06-06
 
 schedule_slots:
-  - start:  8:45
-    end:    9:30
-  - start:  9:30
-    end:   10:15
+  - start: '08:45'
+    end:   '09:30'
+  - start: '09:30'
+    end:   '10:15'
 
-  - start: 10:30
-    end:   11:15
-  - start: 11:15
-    end:   12:00
+  - start: '10:30'
+    end:   '11:15'
+  - start: '11:15'
+    end:   '12:00'
 
-  - start: 13:00
-    end:   13:45
-  - start: 13:45
-    end:   14:30
+  - start: '13:00'
+    end:   '13:45'
+  - start: '13:45'
+    end:   '14:30'
 
-  - start: 14:45
-    end:   15:45
+  - start: '14:45'
+    end:   '15:45'
 
 # short classes are 1 timeslot, otherwise 2
 schedule:
-  - day: 1
+  1:
     classes:
       - id: fr
         loc: 360
@@ -105,7 +106,7 @@ schedule:
         short: true
       - id: chem
         loc: 364
-  - day: 2
+  2:
     classes:
       - id: en
         loc: 368
@@ -115,7 +116,7 @@ schedule:
         loc: 362
       - id: info
         loc: Info room
-  - day: 3
+  3:
     classes:
       - id: gym
         loc: Gym 4
@@ -125,7 +126,7 @@ schedule:
         loc: Drama room
       - id: mat
         loc: 362
-  - day: 4
+  4:
     classes:
       - id: mat
         loc: 362
@@ -135,7 +136,7 @@ schedule:
         loc: 368
       - id: chem
         loc: 364
-  - day: 5
+  5:
     classes:
       - id: fr
         loc: 360
@@ -145,7 +146,7 @@ schedule:
         loc: 362
       - id: fr
         loc: 360
-  - day: 6
+  6:
     classes:
       - id: phys
         loc: 364
diff --git a/main.py b/main.py
new file mode 100644
index 0000000..e1960f6
--- /dev/null
+++ b/main.py
@@ -0,0 +1,80 @@
+from ics import Calendar, Event
+import arrow
+import datetime
+import yaml
+
+with open("config.yml") as f:
+    conf = yaml.safe_load(f.read())
+
+subjects = conf["subjects"]
+vacation_days = conf["vacation_days"]
+start_date = conf["start_date"]
+end_date = conf["end_date"]
+schedule_slots = conf["schedule_slots"]
+schedule = conf["schedule"]
+
+step = datetime.timedelta(days = 1)
+# cycle-day (e.g. 1-6)
+day = 1
+
+cal = Calendar()
+
+current_date = start_date
+
+while current_date <= end_date:
+    have_school = True
+    # Vacations
+    for vacation in vacation_days:
+        if(not vacation.get("single")):
+            if current_date >= vacation["start"] and current_date <= vacation["end"]:
+                have_school = False
+                break
+        else:
+            if current_date == vacation["single"]:
+                have_school = False
+                break
+    # Weekends
+    if current_date.weekday() == 5 or current_date.weekday() == 6:
+        have_school = False
+
+    if not have_school:
+        current_date += step
+        continue
+
+    day_classes = schedule[day]["classes"]
+
+    slot_idx = 0
+    for subject_idx, sched_subject in enumerate(day_classes):
+        subject_id = sched_subject["id"]
+        subject_loc = sched_subject["loc"]
+        is_short = sched_subject.get("short", False)
+
+        subject = subjects[subject_id]
+
+        start_time = schedule_slots[slot_idx]["start"]
+        end_time = schedule_slots[slot_idx]["end"]
+
+        slot_idx += 1
+        if slot_idx >= len(schedule_slots):
+            slot_idx = len(schedule_slots) - 1
+
+        if not is_short:
+            end_time = schedule_slots[slot_idx]["end"]
+            slot_idx += 1
+
+        ev = Event()
+        ev.begin = arrow.get(f"{current_date} {start_time}", tzinfo="local")
+        ev.end = arrow.get(f"{current_date} {end_time}", tzinfo="local")
+        ev.location = str(subject_loc)
+        ev.description = f"Day {day}, {subject_loc}"
+        ev.name = subjects[subject_id]["name"]
+        cal.events.add(ev)
+
+    day += 1
+    if day > len(schedule):
+        day = 1
+
+    current_date += step
+
+with open("cal.ics", "w") as f:
+    f.writelines(cal.serialize_iter())
diff --git a/requirements.txt b/requirements.txt
index dec3251..d6d66f7 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -2,5 +2,6 @@ arrow==1.2.3
 attrs==23.1.0
 ics==0.7.2
 python-dateutil==2.8.2
+PyYAML==6.0.1
 six==1.16.0
 TatSu==5.8.3