diff --git a/.gitignore b/.gitignore
index 8a145bd..15efdab 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1,3 +1,5 @@
 __pycache__
 .venv
-scheme
\ No newline at end of file
+scheme
+answers
+results
\ No newline at end of file
diff --git a/main.py b/main.py
index 705bc69..72981c2 100644
--- a/main.py
+++ b/main.py
@@ -1,21 +1,74 @@
 from fastapi import FastAPI
 import json
 import random
+from pathlib import Path
 
 app = FastAPI()
 
+# student_answers_example = {
+#   "version": 1,
+#   "student": "asd",
+#   "attempt": 0,
+#   "questions": [
+#     {
+#       "id": 4,
+#       "question": "Сколько винтов у теодолита?",
+#       "student_answer": 100
+#     }
+#   ]
+# }
+
+# open files once and use variables after
 with open("questions.json", "r", encoding="UTF-8") as f:
     content = json.load(f)
-    questions_with_answers = content["questions"]
+    all_questions = content["questions"]
+    topics = ["теодолит"]
+    topics_questions = [q for q in all_questions if q.get("topic") in topics]
     remove_keys = ["author", "answer", "topic"]
-    questions_without_answers = [{key: value for key, value in q.items() if key not in remove_keys} for q in questions_with_answers]
+    quiz_questions = [{key: value for key, value in q.items() if key not in remove_keys} for q in topics_questions]
+
+with open("students.json", "r", encoding="UTF-8") as f:
+    content = json.load(f)
+    students = content["students"]
+
+Path("answers").mkdir(parents=True, exist_ok=True)
+Path("results").mkdir(parents=True, exist_ok=True)
+
+def check_answers(student_answers: dict):
+    checked_answers = student_answers
+    for a in checked_answers["questions"]:
+        question_id = a["id"]
+        a["correct_answer"] = next(question["answer"] for question in topics_questions if question["id"] == question_id)
+        a["is_correct"] = a["student_answer"] == a["correct_answer"]
 
-@app.get("/")
-def give_quiz(student: str):
-    quiz_questions = random.sample(questions_without_answers, len(questions_without_answers))  # questions selection would be more complicated
+    checked_answers["correct"] = sum([a["is_correct"] for a in checked_answers["questions"]])
+    checked_answers["correct_percent"] = round(checked_answers["correct"] * 100 / len(checked_answers["questions"]))
+    return checked_answers
+
+@app.get("/students")
+def show_students():
+    return students
+
+@app.get("/give_quiz")
+def give_quiz(student_id, student: str):
+    questions_for_student = random.sample(quiz_questions, len(quiz_questions))[:1]  # random order and only first n questions
     return {
         "version": 1,
+        "student_id": student_id,
         "student": student,
         "attempt": 0, # TODO how to count attempts?
-        "questions": quiz_questions
-    }
\ No newline at end of file
+        "questions": questions_for_student
+    }
+
+@app.get("/get_student_answers")
+def get_answers(student_answers: str):
+    json_answers = json.loads(student_answers)
+    print(json_answers)
+    path_to_answers = f'answers/{json_answers["student"]}_{json_answers["attempt"]}.json'
+    with open(path_to_answers, 'w', encoding='utf-8') as f:
+        json.dump(json_answers, f, ensure_ascii=False)
+
+    path_to_results = f'results/{json_answers["student"]}_{json_answers["attempt"]}.json'
+    with open(path_to_results, 'w', encoding='utf-8') as f:
+        json.dump(check_answers(json_answers), f, ensure_ascii=False)  # TODO move checking to background?
+    return json_answers["student"]
\ No newline at end of file
diff --git a/questions.json b/questions.json
index 4aa957d..c1b99a1 100644
--- a/questions.json
+++ b/questions.json
@@ -28,6 +28,13 @@
             "author": "GT",
             "question": "Как называется прибор для измерения превышений?",
             "answer": "нивелир"
+        },
+        {
+            "id": 4,
+            "topic": "теодолит",
+            "author": "GT",
+            "question": "Сколько винтов у теодолита?",
+            "answer": 520
         }
     ]
 }
\ No newline at end of file
diff --git a/students.json b/students.json
index 6371f09..27d98f4 100644
--- a/students.json
+++ b/students.json
@@ -2,6 +2,7 @@
     "version": 1,
     "students": [
         {
+            "id": 1,
             "name": "Екатерина Александровна Щербацкая",
             "professor": "Михаил Иванович Кознышев"
         }