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.
//package com.company;
import java.io.*;
import java.util.*;

public class Main {

    static int n,m,s,u,v,C=0;
    static ArrayList<Integer> adj[] = new ArrayList [5005];
    static ArrayList<Integer> adj_rev[] = new ArrayList [5005];
    static int hasComp[]=new int[5005];
    static int indegree[]=new int[5005];
    static boolean vis[]=new boolean[5005];
    static ArrayList<Integer> finished= new ArrayList<>();

    static void dfs(int u)
    {
        vis[u]=true;
        for(Integer v:adj[u])
            if(!vis[v])
                dfs(v);
        finished.add(u);
    }

    static void dfs_rev(int u)
    {
        vis[u]=true;
        hasComp[u]=C;
      //  System.out.println(u+" "+hasComp[u]);
        for(Integer v:adj_rev[u])
            if(!vis[v])
                dfs_rev(v);
    }

    public static void main(String[] args) {
        InputReader in = new InputReader(System.in);
        PrintWriter w = new PrintWriter(System.out);

        n=in.nextInt();m=in.nextInt();s=in.nextInt();
        for( int i=0; i<=n; i++){
            adj[i]=new ArrayList<Integer>();
            adj_rev[i]=new ArrayList<Integer>();
        }
        for( int i=0; i<m; i++){
            u=in.nextInt();
            v=in.nextInt();
            adj[u].add(v);
            adj_rev[v].add(u);


        }
        for( int i=1; i<=n; i++){
            if(!vis[i]){
                dfs(i);
            }
        }
        Collections.reverse(finished);
        Arrays.fill(vis,false);

        for( Integer i:finished)
            if(!vis[i]){
                C++;
                dfs_rev(i);
            }
        for( int i=1; i<=n; i++){
            for(Integer v:adj[i])
            {
                int c1=hasComp[i];
                int c2=hasComp[v];
                if(c1==c2)continue;
                indegree[c2]++;
            }
        }
        int ans=0;
        //w.println(hasComp[s]);
        indegree[hasComp[s]]=1;
        for( int i=1; i<=C; i++){
            if(indegree[i]==0){
              //  w.println(i);
                ans++;
            }
        }
        w.print(ans);

        w.close();
    }


    static class InputReader {

        private final InputStream stream;
        private final byte[] buf = new byte[8192];
        private int curChar, snumChars;

        public InputReader(InputStream st) {
            this.stream = st;
        }

        public int read() {
            if (snumChars == -1)
                throw new InputMismatchException();
            if (curChar >= snumChars) {
                curChar = 0;
                try {
                    snumChars = stream.read(buf);
                } catch (IOException e) {
                    throw new InputMismatchException();
                }
                if (snumChars <= 0)
                    return -1;
            }
            return buf[curChar++];
        }

        public int nextInt() {
            int c = read();
            while (isSpaceChar(c)) {
                c = read();
            }
            int sgn = 1;
            if (c == '-') {
                sgn = -1;
                c = read();
            }
            int res = 0;
            do {
                res *= 10;
                res += c - '0';
                c = read();
            } while (!isSpaceChar(c));
            return res * sgn;
        }

        public long nextLong() {
            int c = read();
            while (isSpaceChar(c)) {
                c = read();
            }
            int sgn = 1;
            if (c == '-') {
                sgn = -1;
                c = read();
            }
            long res = 0;
            do {
                res *= 10;
                res += c - '0';
                c = read();
            } while (!isSpaceChar(c));
            return res * sgn;
        }

        public int[] nextIntArray(int n) {
            int a[] = new int[n];
            for (int i = 0; i < n; i++) {
                a[i] = nextInt();
            }
            return a;
        }

        public String readString() {
            int c = read();
            while (isSpaceChar(c)) {
                c = read();
            }
            StringBuilder res = new StringBuilder();
            do {
                res.appendCodePoint(c);
                c = read();
            } while (!isSpaceChar(c));
            return res.toString();
        }

        public String nextLine() {
            int c = read();
            while (isSpaceChar(c))
                c = read();
            StringBuilder res = new StringBuilder();
            do {
                res.appendCodePoint(c);
                c = read();
            } while (!isEndOfLine(c));
            return res.toString();
        }

        public boolean isSpaceChar(int c) {
            return c == ' ' || c == '\n' || c == '\r' || c == '\t' || c == -1;
        }

        private boolean isEndOfLine(int c) {
            return c == '\n' || c == '\r' || c == -1;
        }

    }

}