#include <bits/stdc++.h>
using namespace std;
vector<long long int> vect[5001];
bool visited[5001] = {false};
bool visited1[5001] = {false};
long long int x = 0;
void dfs(long long int s1) {
  visited1[s1] = true;
  x++;
  for (long long int i = 0; i < vect[s1].size(); i++) {
    if (!visited1[vect[s1][i]]) dfs(vect[s1][i]);
  }
}
void dfs1(long long int s1) {
  visited[s1] = true;
  for (long long int i = 0; i < vect[s1].size(); i++) {
    if (!visited[vect[s1][i]]) dfs1(vect[s1][i]);
  }
}
int main() {
  ios_base::sync_with_stdio(false), cin.tie(NULL), cout.tie(NULL);
  long long int n, m, s;
  cin >> n >> m >> s;
  long long int i, a, b;
  for (i = 0; i < m; i++) {
    cin >> a >> b;
    vect[a].push_back(b);
  }
  long long int j, c = 0;
  for (j = 0; j < vect[s].size(); j++) dfs1(vect[s][j]);
  vector<pair<long long int, long long int> > vect1;
  for (i = 1; i <= n; i++) {
    if (!visited[i] && i != s) {
      x = 0;
      memset(visited1, false, sizeof(visited1));
      dfs(i);
      vect1.push_back(make_pair(x, i));
    }
  }
  sort(vect1.begin(), vect1.end());
  reverse(vect1.begin(), vect1.end());
  for (i = 0; i < vect1.size(); i++) {
    if (!visited[vect1[i].second]) {
      c++;
      dfs1(vect1[i].second);
    }
  }
  cout << c;
  return 0;
}
