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

public class ReachabilityFromTheCapital implements Closeable {

    private InputReader in = new InputReader(System.in);
    private PrintWriter out = new PrintWriter(System.out);
  
    public void solve() {
        int n = in.ni(), m = in.ni(), s = in.ni() - 1;
        for (int i = 0; i < n; i++) {
            graph.add(new ArrayList<>());
            reverse.add(new ArrayList<>());
        }
        for (int i = 0; i < m; i++) {
            int u = in.ni() - 1, v = in.ni() - 1;
            graph.get(u).add(v);
            reverse.get(v).add(u);
        }
        visited = new boolean[n];
        for (int i = 0; i < n; i++) {
            if (!visited[i]) dfs1(i);
        }
        
        visited = new boolean[n];
        int[] idx = new int[n];
        for (int i = 0; i < n; i++) {
            int node = order.get(n - i - 1);
            if (!visited[node]) {
                component.clear();
                dfs2(node);
                for (int v : component) {
                    idx[v] = components.size();
                }
                components.add(new ArrayList<>(component));
            }
        }
        int[] degree = new int[components.size()];
        for (int u = 0; u < n; u++) {
            for (int v : graph.get(u)) {
                if (idx[u] != idx[v]) {
                    degree[idx[v]]++;
                }
            }
        }
        int result = 0;
        for (int i = 0; i < degree.length; i++) {
            if (i != idx[s] && degree[i] == 0) {
                result++;
            }
        }
        out.println(result);
    }
    
    private boolean[] visited;
    private List<List<Integer>> graph = new ArrayList<>(), reverse = new ArrayList<>(), components = new ArrayList<>();
    private List<Integer> order = new ArrayList<>(), component = new ArrayList<>();
    
    private void dfs1(int node) {
        visited[node] = true;
        for (int next : graph.get(node)) {
            if (!visited[next]) {
                dfs1(next);
            }
        }
        order.add(node);
    }
    
    private void dfs2(int node) {
        visited[node] = true;
        component.add(node);
        for (int next : reverse.get(node)) {
            if (!visited[next]) {
                dfs2(next);
            }
        }
    }
    
    @Override
    public void close() throws IOException {
        in.close();
        out.close();
    }

    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 ni() {
            return Integer.parseInt(next());
        }

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

        public void close() throws IOException {
            reader.close();
        }
    }

    public static void main(String[] args) throws IOException {
        try (ReachabilityFromTheCapital instance = new ReachabilityFromTheCapital()) {
            instance.solve();
        }
    }
}
