15 6 18 3 7 2 4 13 9 17 20 serch 13
12 5 18 2 9 15 17 19 insert 13
15 5 16 3 12 20 10 6 7 13 18 23 delete 13
15 5 16 3 12 20 10 6 7 13 18 23 delete 16
15 5 16 3 12 20 10 6 7 13 18 23 delete 5