12-01: https://www.acmicpc.net/problem/11656
12-02: https://www.acmicpc.net/problem/10826
12-03: https://www.acmicpc.net/problem/2579
12-04: https://www.acmicpc.net/problem/13300
12-05: https://www.acmicpc.net/problem/10163
12-06: https://www.acmicpc.net/problem/2559
12-07: https://www.acmicpc.net/problem/2304
12-08: https://www.acmicpc.net/problem/15649
12-09: https://www.acmicpc.net/problem/15650
12-10: https://www.acmicpc.net/problem/1904
12-11: https://www.acmicpc.net/problem/14696
12-12: https://www.acmicpc.net/problem/1021
12-13: https://www.acmicpc.net/problem/13305
12-14: https://www.acmicpc.net/problem/15657
12-15: https://www.acmicpc.net/problem/3273