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.OutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.PrintWriter;
import java.util.Collection;
import java.util.InputMismatchException;
import java.io.IOException;
import java.io.FileInputStream;
import java.util.ArrayList;
import java.util.Queue;
import java.util.Comparator;
import java.util.LinkedList;
import java.util.Collections;
import java.io.InputStream;

/**
 * Built using CHelper plug-in
 * Actual solution is at the top
 */
public class Main {
    public static void main(String[] args) {
        InputStream inputStream = System.in;
        OutputStream outputStream = System.out;
        InputReader in = new InputReader(inputStream);
        PrintWriter out = new PrintWriter(outputStream);
        EReachabilityFromTheCapital solver = new EReachabilityFromTheCapital();
        solver.solve(1, in, out);
        out.close();
    }

    static class EReachabilityFromTheCapital {
        private int n;
        private int m;
        private int s;
        private boolean[] vis;
        private boolean[] vis2;
        private int cnt;
        private ArrayList<Integer>[] graph;

        private void bfs(int start) {
            Queue<Integer> queue = new LinkedList<>();
            queue.offer(start);
            vis[start] = true;
            while (!queue.isEmpty()) {
                int v = queue.poll();
                for (int w : graph[v]) {
                    if (!vis[w]) {
                        vis[w] = true;
                        queue.offer(w);
                    }
                }
            }
        }

        private void dfs(int start) {
            vis2[start] = true;
            cnt++;
            for (int x : graph[start]) {
                if (!vis[x] && !vis2[x]) dfs(x);
            }
        }

        public void solve(int testNumber, InputReader in, PrintWriter out) {
            n = in.nextInt();
            m = in.nextInt();
            s = in.nextInt();
            graph = new ArrayList[n + 1];
            for (int i = 0; i <= n; i++) graph[i] = new ArrayList<>();
            for (int i = 0; i < m; i++) {
                graph[in.nextInt()].add(in.nextInt());
            }
            ArrayList<Util.Pair<Integer>> al = new ArrayList<>();
            vis = new boolean[n + 1];
            bfs(s);
//        out.println(Arrays.toString(vis));
            for (int i = 1; i <= n; i++) {
                if (!vis[i]) {
                    vis2 = new boolean[n + 1];
                    cnt = 0;
                    dfs(i);
                    al.add(new Util.Pair<>(cnt, i));
                }
            }
//        out.println(Arrays.toString(val));

            int ans = 0;
            Collections.sort(al, Comparator.comparingInt(o -> o.x));
//        out.println(al.toString());
            for (int i = al.size() - 1; i >= 0; i--) {
                int node = al.get(i).y;
                if (!vis[node]) {
                    bfs(node);
                    ans++;
                }
            }
            out.println(ans);
        }

    }

    static class Util {
        public static class Pair<T> {
            public T x;
            public T y;

            public Pair(T x, T y) {
                this.x = x;
                this.y = y;
            }

            public boolean equals(Object obj) {
                if (obj == this) return true;
                if (!(obj instanceof Util.Pair)) return false;
                Util.Pair<T> pair = (Util.Pair<T>) obj;
                return this.x == pair.x && this.y == pair.y;
            }

            public String toString() {
                return ("(" + this.x + "," + this.y + ")");
            }

            public int hashCode() {
                return (this.x + " " + this.y).hashCode();
            }

        }

    }

    static class InputReader {
        private InputStream stream;
        private byte[] buf = new byte[8192];
        private int curChar;
        private int numChars;

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

        public InputReader(FileInputStream file) {
            this.stream = file;
        }

        public int read() {
            if (numChars == -1) {
                throw new InputMismatchException();
            }
            if (curChar >= numChars) {
                curChar = 0;
                try {
                    numChars = stream.read(buf);
                } catch (IOException e) {
                    throw new InputMismatchException();
                }
                if (numChars <= 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 {
                if (c < '0' || c > '9') {
                    throw new InputMismatchException();
                }
                res = (res << 3) + (res << 1) + c - '0';
                c = read();
            } while (!isSpaceChar(c));
            return res * sgn;
        }

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

    }
}

