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.AbstractCollection;
import java.util.PriorityQueue;
import java.util.InputMismatchException;
import java.io.IOException;
import java.io.InputStream;
import java.util.ArrayList;

/**
 * Built using CHelper plug-in
 * Actual solution is at the top
 *
 * @author kanak893
 */
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);
        TaskE solver = new TaskE();
        solver.solve(1, in, out);
        out.close();
    }

    static class TaskE {
        public void solve(int testNumber, InputReader fi, PrintWriter out) {
            int n, m, s, i, j;
            n = fi.nextInt();
            m = fi.nextInt();
            s = fi.nextInt();
            Graph g = new Graph(n, m);
            for (i = 0; i < m; i++) {
                g.addEdge(fi.nextInt(), fi.nextInt());
            }
            g.dfs1(s);
            for (i = 1; i <= n; i++) {
                if (!g.good[i]) {
                    g.reset();
                    int y = g.dfs2(i);
                    g.pq.add(new Pair(i, y));
                }
            }
            int ans = 0;
            while (!g.pq.isEmpty()) {
                Pair temp = g.pq.poll();
                if (!g.good[temp.index]) {
                    ans++;
                    g.dfs1(temp.index);
                }
            }
            out.println(ans);
        }

    }

    static class Graph {
        int n;
        int m;
        ArrayList<Integer>[] adj;
        boolean[] good;
        boolean[] vis;
        PriorityQueue<Pair> pq;

        Graph(int n, int m) {
            this.n = n;
            this.m = m;
            adj = new ArrayList[n + 1];
            good = new boolean[n + 1];
            vis = new boolean[n + 1];
            pq = new PriorityQueue<>();
            for (int i = 0; i <= n; i++) {
                adj[i] = new ArrayList<>();
            }
        }

        void addEdge(int i, int j) {
            adj[i].add(j);
        }

        void reset() {
            for (int i = 0; i <= n; i++) vis[i] = good[i];
        }

        void dfs1(int s) {
            good[s] = true;
            for (int x : adj[s]) {
                if (!good[x]) dfs1(x);
            }
        }

        int dfs2(int s) {
            int ans = 1;
            vis[s] = true;
            for (int x : adj[s]) {
                if (!vis[x]) {
                    ans += dfs2(x);
                }
            }
            return ans;
        }

    }

    static class Pair implements Comparable<Pair> {
        int index;
        int nodes;

        Pair(int index, int nodes) {
            this.index = index;
            this.nodes = nodes;
        }

        public int compareTo(Pair x) {
            return Integer.compare(x.nodes, this.nodes);
        }

    }

    static class InputReader {
        private InputStream stream;
        private byte[] buf = new byte[8192];
        private int curChar;
        private int snumChars;
        private InputReader.SpaceCharFilter filter;

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

        public int snext() {
            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 = snext();
            while (isSpaceChar(c))
                c = snext();
            int sgn = 1;
            if (c == '-') {
                sgn = -1;
                c = snext();
            }
            int res = 0;
            do {
                if (c < '0' || c > '9')
                    throw new InputMismatchException();
                res *= 10;
                res += c - '0';
                c = snext();
            } while (!isSpaceChar(c));
            return res * sgn;
        }

        public boolean isSpaceChar(int c) {
            if (filter != null)
                return filter.isSpaceChar(c);
            return c == ' ' || c == '\n' || c == '\r' || c == '\t' || c == -1;
        }

        public interface SpaceCharFilter {
            public boolean isSpaceChar(int ch);

        }

    }
}

