diff --git a/migrations/20240727123308_initial.sql b/migrations/20240727123308_initial.sql
index 1bed51f..1c81572 100644
--- a/migrations/20240727123308_initial.sql
+++ b/migrations/20240727123308_initial.sql
@@ -22,11 +22,7 @@ BEGIN
 END;
 $$;
 
-CREATE TRIGGER lng_upd_trg
-    BEFORE UPDATE
-    ON languages
-    FOR EACH ROW
-EXECUTE FUNCTION lng_upd_trg_fn();
+CREATE TRIGGER lng_upd_trg BEFORE UPDATE ON languages FOR EACH ROW EXECUTE FUNCTION lng_upd_trg_fn();
 
 
 
@@ -60,19 +56,54 @@ CREATE INDEX ON contests USING BTREE (id);
 
 
 
-CREATE TABLE IF NOT EXISTS contest_problem
+CREATE TABLE IF NOT EXISTS tasks
 (
+    id            SERIAL       NOT NULL,
     contest_id    INT          REFERENCES contests ON DELETE CASCADE,
     problem_id    INT          REFERENCES problems ON DELETE CASCADE,
     position      INT          NOT NULL,
     position_name VARCHAR(10)  NOT NULL,     -- problem name like: A,B,A1,etc
     UNIQUE (contest_id,problem_id),
     UNIQUE (contest_id,position),
-    UNIQUE (contest_id,position_name)
+    UNIQUE (contest_id,position_name),
+    PRIMARY KEY (id)
 );
 
-CREATE INDEX ON contest_problem USING BTREE (contest_id);
-CREATE INDEX ON contest_problem USING BTREE (problem_id);
+CREATE INDEX ON tasks USING BTREE (id);
+CREATE INDEX ON tasks USING BTREE (contest_id);
+CREATE INDEX ON tasks USING BTREE (problem_id);
+
+
+
+
+CREATE TABLE IF NOT EXISTS testgroups
+(
+    id               serial          NOT NULL,
+    problem_id       INT             REFERENCES problems ON DELETE CASCADE,
+    testing_strategy INT             NOT NULL,
+
+    PRIMARY KEY (id)
+);
+
+CREATE INDEX ON testgroups USING BTREE (id);
+CREATE INDEX ON testgroups USING BTREE (problem_id);
+
+
+
+
+CREATE TABLE IF NOT EXISTS subtasks
+(
+    id            SERIAL       NOT NULL,
+    contest_id    INT          REFERENCES contests ON DELETE CASCADE,
+    testgroup_id  INT          REFERENCES testgroups ON DELETE CASCADE,
+    task_id       INT          REFERENCES tasks ON DELETE CASCADE,
+    UNIQUE (contest_id,testgroup_id),
+    PRIMARY KEY (id)
+);
+
+CREATE INDEX ON subtasks USING BTREE (id);
+CREATE INDEX ON subtasks USING BTREE (contest_id);
+CREATE INDEX ON subtasks USING BTREE (testgroup_id);
 
 
 
@@ -95,26 +126,12 @@ CREATE INDEX ON participants USING BTREE (contest_id);
 
 
 
-CREATE TABLE IF NOT EXISTS testgroups
-(
-    id               serial          NOT NULL,
-    problem_id       INT             REFERENCES problems ON DELETE CASCADE,
-    testing_strategy INT             NOT NULL,
-
-    PRIMARY KEY (id)
-);
-
-CREATE INDEX ON testgroups USING BTREE (id);
-CREATE INDEX ON testgroups USING BTREE (problem_id);
-
-
-
-
 CREATE TABLE IF NOT EXISTS solutions
 (
     id             serial               NOT NULL,
     participant_id INT                  REFERENCES participants ON DELETE CASCADE,
-    problem_id     INT                  REFERENCES problems ON DELETE CASCADE,
+    --problem_id     INT                  REFERENCES problems ON DELETE CASCADE,
+    task_id        INT                  REFERENCES problems ON DELETE CASCADE,
     language_id    INT                  REFERENCES languages ON DELETE CASCADE,
     contest_id     INT                  NOT NULL,
     solution_hash  CHAR(128)            NOT NULL,
@@ -125,7 +142,7 @@ CREATE TABLE IF NOT EXISTS solutions
 );
 
 CREATE INDEX ON solutions USING BTREE (id);
-CREATE INDEX ON solutions USING BTREE (id,participant_id,problem_id,language_id,contest_id);
+CREATE INDEX ON solutions USING BTREE (id,participant_id,task_id,language_id,contest_id);
 
 
 
@@ -162,51 +179,61 @@ CREATE INDEX ON testruns USING BTREE (solution_id);
 
 
 
-CREATE TABLE IF NOT EXISTS participant_problem
+CREATE TABLE IF NOT EXISTS participant_subtask
 (
     participant_id INT     REFERENCES participants ON DELETE CASCADE,
-    problem_id     INT     REFERENCES problems ON DELETE CASCADE,
+    subtask_id     INT     REFERENCES subtasks ON DELETE CASCADE,
+    result         INT     NOT NULL,
+    best_score     INT     NOT NULL
+);
+
+
+
+
+CREATE TABLE IF NOT EXISTS participant_task
+(
+    participant_id INT     REFERENCES participants ON DELETE CASCADE,
+    task_id        INT     REFERENCES tasks ON DELETE CASCADE,
     result         INT     NOT NULL,
     best_score     INT     NOT NULL,
     penalty        INT     NOT NULL
 );
 
-CREATE FUNCTION fill_participant_result() RETURNS TRIGGER AS 
-$$
-BEGIN
-    RAISE NOTICE 'NEW.ID:%, NEW.contest_id:%', NEW.id,NEW.contest_id;
-    INSERT INTO participant_problem (participant_id,problem_id,result,best_score,penalty) SELECT NEW.id,problem_id,0,0,0 FROM contest_problem WHERE contest_id=NEW.contest_id;
+CREATE FUNCTION on_new_participant() RETURNS TRIGGER AS 
+$$ BEGIN
+    --RAISE NOTICE 'NEW.ID:%, NEW.contest_id:%', NEW.id,NEW.contest_id;
+    INSERT INTO participant_task (participant_id,task_id,result,best_score,penalty) SELECT NEW.id,id,0,0,0 FROM tasks WHERE contest_id=NEW.contest_id;
+    INSERT INTO participant_subtask (participant_id,subtask_id,result,best_score) SELECT NEW.id,id,0,0 FROM subtasks WHERE contest_id=NEW.contest_id;
     RETURN NEW;
-END;
-$$ LANGUAGE plpgsql;
+END; $$ LANGUAGE plpgsql;
 
-CREATE TRIGGER fill_participant_result_trg
-    AFTER INSERT
-    ON participants
-    FOR EACH ROW
-EXECUTE FUNCTION fill_participant_result();
+CREATE TRIGGER new_participant_trg AFTER INSERT ON participants FOR EACH ROW EXECUTE FUNCTION on_new_participant();
 
-CREATE FUNCTION fill_problem_result() RETURNS TRIGGER AS 
-$$
-BEGIN
-    INSERT INTO participant_problem (participant_id,problem_id,result,best_score,penalty) SELECT id,NEW.problem_id,0,0,0 FROM participants WHERE contest_id=NEW.contest_id;
+CREATE FUNCTION on_new_task() RETURNS TRIGGER AS 
+$$ BEGIN
+    INSERT INTO participant_task (participant_id,task_id,result,best_score,penalty) SELECT id,NEW.id,0,0,0 FROM participants WHERE contest_id=NEW.contest_id;
+    INSERT INTO subtasks(contest_id,testgroup_id,task_id) SELECT NEW.contest_id,id,NEW.id FROM testgroups WHERE problem_id = NEW.problem_id;
     RETURN NEW;
-END;
-$$ LANGUAGE plpgsql;
+END; $$ LANGUAGE plpgsql;
+
+CREATE TRIGGER new_task_trg AFTER INSERT ON tasks FOR EACH ROW EXECUTE FUNCTION on_new_task();
+
+CREATE FUNCTION on_new_subtask() RETURNS TRIGGER AS 
+$$ BEGIN
+    INSERT INTO participant_subtask (participant_id,subtask_id,result,best_score) SELECT id,NEW.id,0,0 FROM participants WHERE contest_id=NEW.contest_id;
+    RETURN NEW;
+END; $$ LANGUAGE plpgsql;
+
+CREATE TRIGGER new_subtask_trg AFTER INSERT ON subtasks FOR EACH ROW EXECUTE FUNCTION on_new_subtask();
 
-CREATE TRIGGER fill_problem_result_trg
-    AFTER INSERT
-    ON contest_problem
-    FOR EACH ROW
-EXECUTE FUNCTION fill_problem_result();
--- TODO: automatic creating & deleting entries on creating & deleting users & problems to contest
 -- +goose StatementEnd
 
 -- +goose Down
 -- +goose StatementBegin
 DROP FUNCTION IF EXISTS lng_upd_trg_fn CASCADE;
-DROP FUNCTION IF EXISTS fill_participant_result CASCADE;
-DROP FUNCTION IF EXISTS fill_problem_result CASCADE;
+DROP FUNCTION IF EXISTS on_new_participant CASCADE;
+DROP FUNCTION IF EXISTS on_new_task CASCADE;
+DROP FUNCTION IF EXISTS on_new_subtask CASCADE;
 DROP TABLE IF EXISTS tests CASCADE;
 DROP TABLE IF EXISTS solutions CASCADE;
 DROP TABLE IF EXISTS languages CASCADE;
@@ -214,7 +241,9 @@ DROP TABLE IF EXISTS testgroups CASCADE;
 DROP TABLE IF EXISTS testruns CASCADE;
 DROP TABLE IF EXISTS problems CASCADE;
 DROP TABLE IF EXISTS contests CASCADE;
-DROP TABLE IF EXISTS contest_problem CASCADE;
+DROP TABLE IF EXISTS tasks CASCADE;
+DROP TABLE IF EXISTS subtasks CASCADE;
 DROP TABLE IF EXISTS participants CASCADE;
-DROP TABLE IF EXISTS participant_problem CASCADE;
+DROP TABLE IF EXISTS participant_task CASCADE;
+DROP TABLE IF EXISTS participant_subtask CASCADE;
 -- +goose StatementEnd
diff --git a/todo.md b/todo.md
index 1d2f062..12f6971 100644
--- a/todo.md
+++ b/todo.md
@@ -1,3 +1,4 @@
 # TODO LIST:
 
 * create contest groups
+* add ability to change testset