Competitions

# Breadth First Search

# Maximum by minimum

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

#### Input

First line contains three positive integers **n**, **m** и **s** (**1** ≤ **s** ≤ **n** ≤ **5000**, **1** ≤ **m** ≤ **20000**) - 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.

#### Output

Print the required shortest distance.

Input example #1

3 5 3 1 2 2 1 3 1 2 3 3 3

Output example #1

2

Input example #2

5 4 5 1 2 2 3 3 4 4 5

Output example #2

4