#include <bits/stdc++.h>
using namespace std;
const int N = 5005;
vector<int> adj[N];
bool visited[N];
bool reach[N];
pair<int, int> has[N];
int cnt = 0;
void dfs(int s) {
  if (!visited[s]) {
    visited[s] = 1;
    reach[s] = 1;
    for (int i = 0; i < adj[s].size(); i++) {
      dfs(adj[s][i]);
    }
  }
}
void dfs2(int s, int a) {
  if (!visited[s]) {
    visited[s] = 1;
    if (reach[s] == 0) has[a].first++;
    for (int i = 0; i < adj[s].size(); i++) {
      dfs2(adj[s][i], a);
    }
  }
}
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(0);
  cout.tie(0);
  int n, m, s;
  cin >> n >> m >> s;
  s--;
  for (int i = 0; i < m; i++) {
    int a, b;
    cin >> a >> b;
    a--;
    b--;
    adj[a].push_back(b);
  }
  dfs(s);
  for (int i = 0; i < n; i++) {
    has[i].second = i;
  }
  for (int i = 0; i < n; i++) {
    if (!reach[i]) {
      memset(visited, 0, sizeof(visited));
      dfs2(i, i);
    }
  }
  sort(has, has + N);
  reverse(has, has + N);
  int ans = 0;
  cnt = 0;
  memset(visited, 0, sizeof(visited));
  for (int i = 0; i < n; i++) {
    if (!reach[has[i].second]) {
      dfs(has[i].second);
      memset(visited, 0, sizeof(visited));
      ans++;
    }
  }
  cout << ans;
  return 0;
}
