diff --git a/app/main.py b/app/main.py
index fa56336e..e1f0b883 100644
--- a/app/main.py
+++ b/app/main.py
@@ -1 +1,62 @@
-# write your code here
+import dataclasses
+from datetime import datetime
+from typing import List
+import pickle
+
+
+# ----------------- Dataclasses -----------------
+@dataclasses.dataclass
+class Specialty:
+    name: str
+    number: int
+
+
+@dataclasses.dataclass
+class Student:
+    first_name: str
+    last_name: str
+    birth_date: datetime
+    average_mark: float
+    has_scholarship: bool
+    phone_number: str
+    address: str
+
+
+@dataclasses.dataclass
+class Group:
+    specialty: Specialty
+    course: int
+    students: List[Student]
+
+
+# ----------------- Functions -----------------
+def write_groups_information(groups: List[Group]) -> int:
+    """Сохраняет группы в 'groups.pickle', возвращает макс. число студентов"""
+    with open("groups.pickle", "wb") as f:
+        pickle.dump(groups, f)
+    if not groups:
+        return 0
+    max_students = max(len(g.students) for g in groups)
+    return max_students
+
+
+def write_students_information(students: List[Student]) -> int:
+    """Сохраняет студентов в 'students.pickle', возвращает количество"""
+    with open("students.pickle", "wb") as f:
+        pickle.dump(students, f)
+    return len(students)
+
+
+def read_groups_information() -> List[str]:
+    """Читает группы из 'groups.pickle', возвращает уникальные специальности"""
+    with open("groups.pickle", "rb") as f:
+        groups: List[Group] = pickle.load(f)
+    specialty_names = {g.specialty.name for g in groups}
+    return list(specialty_names)
+
+
+def read_students_information() -> List[Student]:
+    """Читает студентов из 'students.pickle'"""
+    with open("students.pickle", "rb") as f:
+        students: List[Student] = pickle.load(f)
+    return students