diff --git a/app/main.py b/app/main.py
index fa56336e..721865b4 100644
--- a/app/main.py
+++ b/app/main.py
@@ -1 +1,64 @@
-# write your code here
+from dataclasses import dataclass
+from datetime import datetime
+import pickle
+
+
+@dataclass
+class Specialty:
+    name: str
+    number: int
+
+
+@dataclass
+class Student:
+    first_name: str
+    last_name: str
+    birth_date: datetime
+    average_mark: float
+    has_scholarship: bool
+    phone_number: int
+    address: str
+
+
+@dataclass
+class Group:
+    specialty: Specialty
+    course: str
+    students: list[Student]
+
+
+def write_groups_information(groups: list[Group]) -> int:
+    max_students = 0
+    with open("groups.pickle", "wb") as f:
+        for group in groups:
+            if len(group.students) > max_students:
+                max_students = len(group.students)
+        pickle.dump(groups, f)
+    return max_students
+
+
+def write_students_information(students: list[Student]) -> int:
+    students_num = 0
+    with open("students.pickle", "wb") as f:
+        for student in students:
+            students_num += 1
+        pickle.dump(students, f)
+    return students_num
+
+
+def read_groups_information() -> set:
+    specialties = []
+    with open("groups.pickle", "rb") as f:
+        groups = pickle.load(f)
+        for group in groups:
+            specialties.append(group.specialty.name)
+    return set(specialties)
+
+
+def read_students_information() -> list[Student]:
+    students_list = []
+    with open("students.pickle", "rb") as f:
+        students = pickle.load(f)
+        for student in students:
+            students_list.append(student)
+    return students_list