[요약] M점에서 시작하여 다른 지점으로 가는 시간은 1시간이 걸린다. 다른 지점으로 갈 수 있다면 1, 갈 수 없다면 0으로 주어진 그래프를 입력받을 때, 각 줄마다 시간별로 도달 가능한 지점을 오름차순으로 출력한다.

She has experimented to create a map of the ocean with valid single-hop routes between each pair of the N (1 <= N <= 100) islands, conveniently numbered 1..N. The routes are one-way (unidirectional), owing to the way the currents push her boat in the ocean. It's possible that a pair of islands is connected by two routes that use different currents and thus provide a bidirectional connection. The map takes care to avoid specifying that a route exists between an island and itself.

Given her starting location M (1 <= M <= N) and a representation of the map, help Bessie determine which islands are one 'hop' away, two 'hops' away, and so on. If Bessie can take multiple different paths to an island, consider only the path with the shortest distance.

By way of example, below are N=4 islands with connectivity as shown (for this example, M=1):

       start--> 1-------->2
                |         |
                |         |
                V         V
                4<--------3

The input for this task is a matrix C where the element at row r, column c is named C_rc (0 <= C_rc <= 1) and, if it has the value 1, means "Currents enable Bessie to travel directly from island r to island c in one time unit". Row C_r has N elements, respectively C_r1..C_rN, each one of which is 0 or 1.

입력

• * Line 1: Two space-separated integers: N and M
• * Lines 2..N+1: Line i+1 contains N space-separated integers: C_r

출력

입출력 예

입력

4 1
0 1 0 1
0 0 1 0
0 0 0 1
0 0 0 0

출력

1
2 4
3

출처:usaco 2011  MAR bronze
요약:pl0892029