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.*;
import java.util.*;

/**
 * Created by kartik.t on 23/05/17.
 */
public class ReachibilityFromCap {

    static HashSet<Integer> graph[];
    static boolean visited[];
    static HashSet<Integer> parents[];


    public static void dfs(int node) {
        visited[node] = true;
        HashSet<Integer> connections = graph[node];
        for (Integer connection : connections) {
            if (!visited[connection]) {
                dfs(connection);
            }
        }
    }

    public static void main(String args[]) throws IOException {
        FastReader in = new FastReader();
        OutputStream outputStream = System.out;
        PrintWriter out = new PrintWriter(outputStream);
        Task.solve(in, out);
        out.close();
    }

    static class Task {
        public static void solve(FastReader in, PrintWriter out) {
            int n = in.nextInt();
            int m = in.nextInt();
            int s = in.nextInt();
            visited = new boolean[n];
            graph = new HashSet[n];
            parents = new HashSet[n];
            for (int i = 0; i < n; i++) {
                graph[i] = new HashSet<>();
                parents[i] = new HashSet<>();
            }
            for (int i = 0; i < m; i++) {
                int x = in.nextInt();
                int y = in.nextInt();
                x--;
                y--;
                graph[x].add(y);
                parents[y].add(x);
            }

            dfs(s-1);

            int ans =0;

//            HashMap<Integer,HashSet<Integer>> hm = new HashMap<>();
            for(int i=0;i<n;i++){
                if(!visited[i]){
                    HashSet<Integer> hs = new HashSet<>();
                    hs.add(i);
                    modifiedDfs(i,hs);
                    boolean addEdge = true;
                    for(Integer node: hs){
                        for(Integer parent: parents[node]){
                            if(!hs.contains(parent)){
                                addEdge = false;
                                break;
                            }
                        }
                        if(!addEdge){
                            break;
                        }
                    }
                    if(addEdge){
                        ans++;
                    }
                }
            }


            System.out.println(ans);
        }

        public static void modifiedDfs(int node,HashSet<Integer> hs) {

            visited[node] = true;
            HashSet<Integer> connections = graph[node];
            for (Integer connection : connections) {
                if (!visited[connection]) {
                    modifiedDfs(connection,hs);
                }
                if(hs.contains(connection)){
                    hs.add(node);
                }
            }
        }

    }

    static class FastReader {
        BufferedReader br;
        StringTokenizer st;

        public FastReader() {
            br = new BufferedReader(new
                    InputStreamReader(System.in));
        }

        String next() {
            while (st == null || !st.hasMoreElements()) {
                try {
                    st = new StringTokenizer(br.readLine());
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
            return st.nextToken();
        }

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

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

        double nextDouble() {
            return Double.parseDouble(next());
        }

        String nextLine() {
            String str = "";
            try {
                str = br.readLine();
            } catch (IOException e) {
                e.printStackTrace();
            }
            return str;
        }
    }
}