http://100.damki.net/problem/22 0.4 http://100.damki.net/answer/22 0.3 http://100.damki.net/problem/23 0.4 http://100.damki.net/answer/23 0.3 http://100.damki.net/problem/28 0.4 http://100.damki.net/answer/28 0.3 http://100.damki.net/problem/17 0.4 http://100.damki.net/answer/17 0.3 http://100.damki.net/problem/19 0.4 http://100.damki.net/answer/19 0.3