Breadth First Search

Maximum by minimum

An oriented unweighted graph is given. Find in it a vertex, the shortest distance from which to the given one is maximum, and print this distance.


First line contains three positive integers n, m и s (1sn5000, 1m20000) - the number of vertices and edges in the graph and the number of given vertex. In the next m lines the graph edges are given. Each edge is given with the pair of numbers - the starting and the ending point.


Print one integer - the required shortest distance.

Time limit 2 second
Memory limit 128 MiB
Input example #1
3 5 3
1 2
2 1
3 1
2 3
3 3
Output example #1