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.
#include <bits/stdc++.h>
using namespace std;
std::vector<int> G[5005];
int vis[5005], vis1[5005];
stack<int> stk;
void dfs(int u) {
  vis[u] = 1;
  for (int v : G[u]) {
    if (!vis[v]) dfs(v);
  }
  stk.push(u);
}
void dfs1(int u) {
  vis1[u] = 1;
  for (int v : G[u]) {
    if (!vis1[v]) dfs1(v);
  }
}
int main(int argc, char const *argv[]) {
  int n, m, C;
  cin >> n >> m >> C;
  for (int i = 0; i < m; ++i) {
    int u, v;
    cin >> u >> v;
    G[u].push_back(v);
  }
  dfs1(C);
  for (int i = 1; i < n + 1; ++i) vis[i] = vis1[i];
  for (int i = 1; i < n + 1; ++i) {
    if (vis[i]) continue;
    dfs(i);
  }
  std::vector<int> dep;
  while (!stk.empty()) {
    dep.push_back(stk.top());
    stk.pop();
  }
  int c = 0;
  for (int i : dep) {
    if (!vis1[i]) {
      c++;
      dfs1(i);
    }
  }
  cout << c << endl;
  return 0;
}
