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.
import java.io.*;
import java.math.*;
import java.util.*;

public class Main {
  public static void main(String[] args) {
    InputStream inputStream = System.in;
    OutputStream outputStream = System.out;
    InputReader in = new InputReader(inputStream);
    PrintWriter out = new PrintWriter(outputStream);
    PP solver = new PP();
    solver.run(1, in, out);
    out.close();
  }

  static class PP {
    int n, m, capital;
    ArrayList<Integer>[] g;
    boolean[] was;
    boolean[] good;
    int reachable;
    ArrayList<Pair> pairs;

    public void run(int testNumber, InputReader in, PrintWriter out) {
      n = in.nextInt();
      m = in.nextInt();
      capital = in.nextInt() - 1;
      g = new ArrayList[n];
      for (int i = 0; i < n; i++) {
        g[i] = new ArrayList<>();
      }
      while (m-- > 0) {
        int x = in.nextInt() - 1;
        int y = in.nextInt() - 1;
        g[x].add(y);
      }
      good = new boolean[n];
      was = new boolean[n];
      Arrays.fill(good, false);
      dfs1(capital);
      pairs = new ArrayList<>();
      for (int i = 0; i < n; i++) {
        if (!good[i]) {
          Arrays.fill(was, false);
          reachable = 0;
          dfs2(i);
          pairs.add(new Pair(reachable, i));
        }
      }
      Collections.sort(pairs);
      int ans = 0;
      for (int i = pairs.size() - 1; i >= 0; i--) {
        int v = pairs.get(i).second;
        if (good[v]) {
          continue;
        }
        Arrays.fill(was, false);
        dfs3(v);
        ans++;
      }
      out.println(ans);
    }

    public void dfs1(int v) { 
      good[v] = true;
      for (int to : g[v]) {
        if (!good[to]) {
          dfs1(to);
        }
      }
    }

    public void dfs2(int v) {
      was[v] = true;
      for (int to : g[v]) {
        if (!was[to]) {
          dfs2(to);
          if (!good[to]) {
            reachable++;
          }
        }
      }
    }

    public void dfs3(int v) {
      was[v] = true;
      good[v] = true;
      for (int to : g[v]) {
        if (!was[to]) {
          dfs3(to);
        }
      }
    }

    public class Pair implements Comparable<Pair> {
      public int first;
      public int second;

      public Pair(int first, int second) {
        this.first = first;
        this.second = second;
      }

      public int compareTo(Pair p) {
        return first == p.first ? Integer.compare(second, p.second) : Integer.compare(first, p.first);
      }
    }
  }

  static class InputReader {
    public BufferedReader reader;
    public StringTokenizer tokenizer;

    public InputReader(InputStream stream) {
      reader = new BufferedReader(new InputStreamReader(stream), 32768);
      tokenizer = null;
    }

    public String next() {
      while (tokenizer == null || !tokenizer.hasMoreTokens()) {
        try {
          tokenizer = new StringTokenizer(reader.readLine());
        } catch (IOException e) {
          throw new RuntimeException(e);
        }
      }
      return tokenizer.nextToken();
    }

    public int nextInt() {
      return Integer.parseInt(next());
    }

    public long nextLong() {
      return Long.parseLong(next());
    }
  }
}