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.
from collections import defaultdict

def topo_sort_variant(graph, n):
    result = []
    visited = [False] * (n+1)

    for i in range(1, n+1):
        if not visited[i]:
            stack = [i]
            while stack:
                node = stack[-1]
                if not visited[node]:
                    visited[node] = True
                    for child in graph[node]:
                        if not visited[child]:
                            stack.append(child)
                else:
                    result.append(stack.pop())
    return result



if __name__ == '__main__':
    min_roads_required = 0
    ncities, nroads, capital = map(int, input().split())

    g = defaultdict(list)

    for i in range(nroads):
        u, v = map(int, input().split())
        g[u].append(v)

    #print("The graph is:", g)
    op = topo_sort_variant(g, ncities)
    #print("The topo sort output is", op)

    visited = [False] * (ncities + 1)

    def topo_dfs(i):
        stack = [i]
        while stack:
            node = stack[-1]
            if not visited[node]:
                visited[node] = True
                for child in g[node]:
                    if not visited[child]:
                        stack.append(child)
            else:
                stack.pop()


    topo_dfs(capital)
    for i in reversed(topo_sort_variant(g, ncities)):
        if not visited[i]:
            topo_dfs(i)
            min_roads_required += 1

    print(min_roads_required)