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.util.*;
import java.io.*;
import static java.lang.Math.*;
public class Main
{  
    static MyScanner scan;
    static PrintWriter pw;
    static int n,m,s;
    static ArrayList<Integer> adj[];
    static int ans = 0;
    static boolean vis[],vis1[];
    static int count;
    public static void main(String[] args) {
        new Thread(null,null,"_",1<<25)
        {
           public void run()
           {
               try
               {
                   solve();
               }
               catch(Exception e)
               {  
                   e.printStackTrace();
                   System.exit(1);
               }
           }
        }.start();
    }
    static void solve() throws IOException
    {
        scan = new MyScanner();
        pw = new PrintWriter(System.out,true);
        StringBuilder sb = new StringBuilder();
        n = ni();
        m = ni();
        s = ni();
        adj = new ArrayList[n+1];
        for(int i=1;i<=n;++i)
            adj[i] = new ArrayList();
        for(int i=0;i<m;++i)
            adj[ni()].add(ni());
        vis = new boolean[n+1];
        vis1 = new boolean[n+1];
        dfs(s);
        int cnt = 0;
        for(int i=1;i<=n;++i)
            if(vis[i])
                ++cnt;
        while(cnt<n)
        {
            Arrays.fill(vis1,false);
            int max = 0,at = -1;
            for(int i=1;i<=n;++i)
                if(!vis1[i] && !vis[i])
                {  
                    dfs1(i);
                    if(max<count)
                    {
                        max = count;
                        at = i;
                    }
                    count = 0;
                    dfs2(i);
                }
            dfs(at);
            cnt+=max;
            ans++;
        }
        pl(ans);
        pw.flush();
        pw.close();
    }
    static void dfs(int v)
    {
        vis[v] = true;
        for(int e:adj[v])
            if(!vis[e])
                dfs(e);
    }
    static void dfs1(int v)
    {
        vis1[v] = true;
        vis[v] = true;
        count++;
        for(int e:adj[v])
            if(!vis[e])
                dfs1(e);
    }
    static void dfs2(int v)
    {
        vis[v] = false;
        for(int e:adj[v])
            if(vis1[e] && vis[e])
                dfs2(e);
    }
    static int ni() throws IOException
    {
        return scan.nextInt();
    }
    static long nl() throws IOException
    {
        return scan.nextLong();
    }
    static double nd() throws IOException
    {
        return scan.nextDouble();
    }
    static String ne() throws IOException
    {
        return scan.next();
    }
    static String nel() throws IOException
    {
        return scan.nextLine();
    }
    static void pl()
    {
        pw.println();
    }
    static void p(Object o)
    {
        pw.print(o+" ");
    }
    static void pl(Object o)
    {
        pw.println(o);
    }
    static void psb(StringBuilder sb)
    {
        pw.print(sb);
    }
    static class MyScanner
    {
        BufferedReader br;
        StringTokenizer st;
        MyScanner()
        {
            br = new BufferedReader(new InputStreamReader(System.in));
        }
        String nextLine()throws IOException
        {
            return br.readLine();
        }
        String next() throws IOException
        {
            if(st==null || !st.hasMoreTokens())
                st = new StringTokenizer(br.readLine());
            return st.nextToken();
        }
        int nextInt() throws IOException
        {
            return Integer.parseInt(next());
        }
        long nextLong() throws IOException
        {
            return Long.parseLong(next());
        }
        double nextDouble() throws IOException
        {
            return Double.parseDouble(next());
        }
    }
}