There are n cities and m roads in Berland. Each road connects a pair of cities. The roads in Berland are one-way.

What is the minimum number of new roads that need to be built to make all the cities reachable from the capital?

New roads will also be one-way.

Input

The first line of input consists of three integers n, m and s (1 ≤ n ≤ 5000, 0 ≤ m ≤ 5000, 1 ≤ s ≤ n) — the number of cities, the number of roads and the index of the capital. Cities are indexed from 1 to n.

The following m lines contain roads: road i is given as a pair of cities u_i, v_i (1 ≤ u_i, v_i ≤ n, u_i ≠ v_i). For each pair of cities (u, v), there can be at most one road from u to v. Roads in opposite directions between a pair of cities are allowed (i.e. from u to v and from v to u).

Output

Print one integer — the minimum number of extra roads needed to make all the cities reachable from city s. If all the cities are already reachable from s, print 0.

Examples

Input

9 9 1
1 2
1 3
2 3
1 5
5 6
6 1
1 8
9 8
7 1


Output

3


Input

5 4 5
1 2
2 3
3 4
4 1


Output

1

Note

The first example is illustrated by the following:

<image>

For example, you can add roads (6, 4), (7, 9), (1, 7) to make all the cities reachable from s = 1.

The second example is illustrated by the following:

<image>

In this example, you can add any one of the roads (5, 1), (5, 2), (5, 3), (5, 4) to make all the cities reachable from s = 5.
#!/usr/bin/env python
from __future__ import division, print_function

import atexit
import os
import sys
from io import IOBase

input = lambda: sys.stdin.readline().rstrip('\r\n')

#region py3k
if sys.version_info[0] < 3:
    from future_builtins import ascii, filter, hex, map, oct, zip

    range = xrange

#endregion

#region fastio
if sys.version_info[0] < 3:
    from cStringIO import StringIO
else:
    from io import BytesIO as StringIO

input = StringIO(os.read(0, os.fstat(0).st_size)).readline

stream = StringIO()
sys.stdout = IOBase()
sys.stdout.flush = lambda: os.write(1, stream.getvalue()) + stream.truncate(0)
sys.stdout.write = lambda s: stream.write(s) if sys.version_info[0] < 3 else stream.write(s.encode())

#endregion


def toposort(graph):
    n = len(graph)
    res, visited = [], [False] * n

    for i in range(n):
        if not visited[i]:
            stack = [i]
            while stack:
                start = stack[-1]
                if not visited[start]:
                    visited[start] = True
                    for child in graph[start]:
                        if not visited[child]:
                            stack.append(child)
                else:
                    res.append(stack.pop())

    return res


def main():
    n, m, s = map(int, input().split())

    graph = [[] for _ in range(n)]
    for i in range(m):
        u, v = map(int, input().split())
        graph[u - 1].append(v - 1)

    res, visited = 0, [False] * n

    def dfs(i):
        stack = [i]
        while stack:
            start = stack[-1]
            if not visited[start]:
                visited[start] = True
                for child in graph[start]:
                    if not visited[child]:
                        stack.append(child)
            else:
                stack.pop()

    dfs(s - 1)
    for i in reversed(toposort(graph)):
        if not visited[i]:
            dfs(i)
            res += 1

    print(res)


if __name__ == '__main__':
    main()
