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.OutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.PrintWriter;
import java.util.List;
import java.util.StringTokenizer;
import java.io.IOException;
import java.io.BufferedReader;
import java.util.Comparator;
import java.io.InputStreamReader;
import java.util.ArrayList;
import java.io.InputStream;

/**
 * Built using CHelper plug-in
 * Actual solution is at the top
 */
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);
        TaskE solver = new TaskE();
        solver.solve(1, in, out);
        out.close();
    }

    static class TaskE {
        public void solve(int testNumber, InputReader in, PrintWriter out) {
            int n = in.nextInt();
            int m = in.nextInt();
            int s = in.nextInt() - 1;
            Vertex[] vs = new Vertex[n];
            for (int i = 0; i < n; ++i) {
                vs[i] = new Vertex(i);
                vs[i].marked = new boolean[n];
            }
            for (int i = 0; i < m; ++i) {
                int x = in.nextInt() - 1;
                int y = in.nextInt() - 1;
                vs[x].adj.add(vs[y]);
            }
            int rem = n - vs[s].dfs(s);
            vs[s].dfs2();
            List<Vertex> remVs = new ArrayList<>();
            for (int i = 0; i < n; ++i) {
                if (i == s || vs[i].taken) continue;
                vs[i].cnt = vs[i].dfs(i);
                remVs.add(vs[i]);
            }
            int res = 0;
            remVs.sort(Comparator.comparing(x -> -x.cnt));
            for (int i = 0; i < remVs.size(); ++i) {
                if (remVs.get(i).taken) continue;
                ++res;
                remVs.get(i).dfs2();
            }
            out.println(res);
        }

        class Vertex {
            int id;
            boolean[] marked;
            boolean taken;
            List<Vertex> adj = new ArrayList<>();
            int cnt = 0;

            Vertex(int id) {
                this.id = id;
            }

            int dfs(int i) {
                int res = 1;
                marked[i] = true;
                for (Vertex v : adj) {
                    if (v.taken || v.marked[i]) continue;
                    res += v.dfs(i);
                }
                return res;
            }

            void dfs2() {
                taken = true;
                for (Vertex v : adj) {
                    if (v.taken) continue;
                    v.dfs2();
                }
            }

        }

    }

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

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

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

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

    }
}

