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.DataInputStream;
import java.io.FileInputStream;
import java.io.IOException;
import java.lang.reflect.Array;
import java.util.*;
public class codeforces {

    static class pair
    {
        int size;
        int n;
        pair(int a)
        {
            n=a;
        }
        pair(int a,int b)
        {
            n=a;
            size=b;
        }
    }

    static class comp implements Comparator<pair>
    {

        @Override
        public int compare(pair o1, pair o2) {
            return -1*Integer.compare(o1.size,o2.size);
        }
    }



    public static void main(String[] args) throws IOException {

        Reader  sc=new Reader();
        int n=sc.nextInt();
        int m=sc.nextInt();
        int s=sc.nextInt();

        ArrayList<Integer>[] list=new ArrayList[n+1];
        ArrayList<Integer>[] reach=new ArrayList[n+1];


        for(int i=0;i<=n;i++) {
            list[i] = new ArrayList<>();
            reach[i]=new ArrayList<>();
        }

        int u,v;
        for(int i=1;i<=m;i++)
        {
            u=sc.nextInt();
            v=sc.nextInt();
            list[u].add(v);
        }

        HashSet<Integer> union=new HashSet<>();
        ArrayList<Integer> order=new ArrayList<>();
        dfs(s,list,union,order);
        for(int i=1;i<=n;i++)
        {
            if(union.contains(i))
                continue;
            HashSet<Integer> temp=new HashSet<>();
            dfs(i,list,union,order);
        }

        int ans=0;

/*
        for(int i=1;i<=n;i++)
            System.out.println(reach[i]);
*/


        HashSet<Integer> check=new HashSet<>();
        dfs1(s,list,check);

        for(int i=order.size()-1;i>=0;i--)
        {
            int a=order.get(i);
          //  System.out.println("A->"+a);

            if(check.size()==n)
                break;

            if(check.contains(a))
                continue;

            check.add(a);
            ans++;

            dfs1(a,list,check);

        }
        System.out.println(ans);





        }

    public static void dfs1(int i, ArrayList<Integer>[] list,HashSet<Integer> set)
    {
        set.add(i);
        for (Integer temp : list[i]) {
            if(!set.contains(temp))
                dfs1(temp,list,set);
        }

    }

        public static void dfs(int i, ArrayList<Integer>[] list,HashSet<Integer> set,ArrayList<Integer> order)
        {
            set.add(i);
            for (Integer temp : list[i]) {
                if(!set.contains(temp))
                    dfs(temp,list,set,order);
            }
        //    System.out.println("Ended:"+i);
            order.add(i);

        }










    static class Reader
    {
        final private int BUFFER_SIZE = 1 << 16;
        private DataInputStream din;
        private byte[] buffer;
        private int bufferPointer, bytesRead;

        public Reader()
        {
            din = new DataInputStream(System.in);
            buffer = new byte[BUFFER_SIZE];
            bufferPointer = bytesRead = 0;
        }

        public Reader(String file_name) throws IOException
        {
            din = new DataInputStream(new FileInputStream(file_name));
            buffer = new byte[BUFFER_SIZE];
            bufferPointer = bytesRead = 0;
        }

        public String readLine() throws IOException
        {
            byte[] buf = new byte[64]; // line length
            int cnt = 0, c;
            while ((c = read()) != -1)
            {
                if (c == '\n')
                    break;
                buf[cnt++] = (byte) c;
            }
            return new String(buf, 0, cnt);
        }

        public int nextInt() throws IOException
        {
            int ret = 0;
            byte c = read();
            while (c <= ' ')
                c = read();
            boolean neg = (c == '-');
            if (neg)
                c = read();
            do
            {
                ret = ret * 10 + c - '0';
            }  while ((c = read()) >= '0' && c <= '9');

            if (neg)
                return -ret;
            return ret;
        }

        public long nextLong() throws IOException
        {
            long ret = 0;
            byte c = read();
            while (c <= ' ')
                c = read();
            boolean neg = (c == '-');
            if (neg)
                c = read();
            do {
                ret = ret * 10 + c - '0';
            }
            while ((c = read()) >= '0' && c <= '9');
            if (neg)
                return -ret;
            return ret;
        }

        public double nextDouble() throws IOException
        {
            double ret = 0, div = 1;
            byte c = read();
            while (c <= ' ')
                c = read();
            boolean neg = (c == '-');
            if (neg)
                c = read();

            do {
                ret = ret * 10 + c - '0';
            }
            while ((c = read()) >= '0' && c <= '9');

            if (c == '.')
            {
                while ((c = read()) >= '0' && c <= '9')
                {
                    ret += (c - '0') / (div *= 10);
                }
            }

            if (neg)
                return -ret;
            return ret;
        }

        private void fillBuffer() throws IOException
        {
            bytesRead = din.read(buffer, bufferPointer = 0, BUFFER_SIZE);
            if (bytesRead == -1)
                buffer[0] = -1;
        }

        private byte read() throws IOException
        {
            if (bufferPointer == bytesRead)
                fillBuffer();
            return buffer[bufferPointer++];
        }

        public void close() throws IOException
        {
            if (din == null)
                return;
            din.close();
        }
    }

}