#include <bits/stdc++.h>
using namespace std;
const int maxn = 1e6 + 2;
long long int i, j, n, m, s, ans = 0, cnt = 0;
vector<pair<long long int, long long int> > nf;
vector<long long int> graph[maxn];
bool foundd[maxn];
void dfs(long long int u, bool found[]) {
  if (!foundd[u]) ++ans;
  found[u] = true;
  vector<long long int>::iterator it;
  for (it = graph[u].begin(); it != graph[u].end(); ++it) {
    if (!found[*it]) dfs(*it, found);
  }
}
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);
  cout.tie(NULL);
  cin >> n >> m >> s;
  bool found[5200], isreachable[5200];
  for (i = 0; i < m; ++i) {
    long long int u, v;
    cin >> u >> v;
    graph[u].push_back(v);
  }
  memset(found, false, sizeof(found));
  dfs(s, found);
  for (i = 1; i <= n; ++i) foundd[i] = found[i];
  for (i = 1; i <= n; ++i) {
    if (!foundd[i]) {
      bool found1[5001];
      memset(found1, false, sizeof(found1));
      ans = 0;
      dfs(i, found1);
      nf.push_back(make_pair(ans, i));
    }
  }
  sort(nf.begin(), nf.end(), greater<pair<long long int, long long int> >());
  for (i = 0; i < nf.size(); ++i) {
    if (!foundd[nf[i].second]) {
      bool found1[5001];
      memset(found1, false, sizeof(found1));
      dfs(nf[i].second, found1);
      ++cnt;
      for (j = 1; j <= n; ++j)
        if (found1[j]) foundd[j] = true;
    }
  }
  cout << cnt;
}
