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.*;
import java.math.*;
import java.text.*;
import java.util.*;
import java.util.regex.*;

public class Solution 
{
    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;
	    }
	}
    
    public static ArrayList<Integer>[] list;
    public static boolean[] vis;
    public static int[] parent;
    public static int subsize;
    public static PriorityQueue<pair> pq;
    
    public static void bfs(int x)
    {
        vis[x]=true;
        ArrayDeque<Integer> qu=new ArrayDeque<Integer>();
        qu.add(x);
        while(!qu.isEmpty())
        {
            int nd=qu.remove();
            for(int i=0;i<list[nd].size();i++)
            {
                //union(nd,list[nd].get(i));
                if(!vis[list[nd].get(i)])
                {
                    vis[list[nd].get(i)]=true;
                    qu.add(list[nd].get(i));
                }
            }
        }
    }
    public static void dfs(int x)
    {
        vis[x]=true;
        subsize++;
        for(int i=0;i<list[x].size();i++)
        {
            if(!vis[list[x].get(i)])
            {
                dfs(list[x].get(i));
            }
        }
    }
    static class pair
    {
        int vertex;
        int size;
        pair(int a1,int a2)
        {
            vertex=a1;
            size=a2;
        }
    }
    static class Mycomp implements Comparator<pair>
    {
        public int compare(pair p1,pair p2)
        {
            return(p2.size-p1.size);
        }
    }
    public static void main(String[] args) throws IOException 
    {
        InputReader in=new InputReader(System.in);
        int n=in.nextInt();
        int m=in.nextInt();
        int s=in.nextInt();
        list=new ArrayList[n+1];
        vis=new boolean[n+1];
        for(int i=0;i<=n;i++)
        {
            list[i]=new ArrayList<Integer>();
        }
        for(int i=0;i<m;i++)
        {
            int v1=in.nextInt();
            int v2=in.nextInt();
            list[v1].add(v2);
        }
        Mycomp cp=new Mycomp();
        pq=new PriorityQueue<pair>(cp);
        for(int i=1;i<=n;i++)
        {
            subsize=0;
            Arrays.fill(vis,false);
            dfs(i);
            pq.add(new pair(i,subsize));
        }
        Arrays.fill(vis,false);
        bfs(s);
        int count=0;
        
        while(!pq.isEmpty())
        {
            int ver=pq.peek().vertex;
            pq.poll();
            if(!vis[ver])
            {
                count++;
                dfs(ver);
            }
        }
        
        System.out.println(count);
    }
}
