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.IOException;
import java.io.PrintWriter;
import java.util.ArrayDeque;
import java.util.ArrayList;

public class P999E3 {
    private static ArrayList<ArrayList<Integer>> list;
    private static boolean[] visited;
    private static final ArrayDeque<Integer> stack = new ArrayDeque<>();

    private static void dfs(int u, boolean p) {
        if (p) {
            if (visited[u])
                return;
            visited[u] = true;
        } else {
            if (!visited[u])
                return;
            visited[u] = false;
        }
        for (Integer v : list.get(u))
            dfs(v, p);
        if (p)
            stack.push(u);
    }

    public static void main(String[] args) throws IOException {
        InputReader2 scan = new InputReader2();
        PrintWriter pw = new PrintWriter(System.out);
        int n = scan.nextInt();
        int m = scan.nextInt();
        int start = scan.nextInt();
        list = new ArrayList<>(n + 1);
        visited = new boolean[n + 1];
        for (int i = 0; i <= n; i++)
            list.add(new ArrayList<>());
        for (int i = 0; i < m; i++) {
            int u = scan.nextInt();
            int v = scan.nextInt();
            list.get(u).add(v);
        }
        for (int i = 1; i <= n; i++) {
            dfs(i, true);
        }
        dfs(start, false);
        int count = 0;
        while (!stack.isEmpty()) {
            int u = stack.pop();
            if (visited[u]) {
                dfs(u, false);
                count++;
            }
        }
        pw.println(count);
        pw.close();
    }

    private static class InputReader2 {
        private final int BUFFER_SIZE = 1 << 16;
        private final DataInputStream dis;
        private final byte[] buffer;
        private int bufferPointer, bytesRead;

        public InputReader2() {
            dis = new DataInputStream(System.in);
            buffer = new byte[BUFFER_SIZE];
            bufferPointer = bytesRead = 0;
        }

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

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

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