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.Arrays;
import java.util.InputMismatchException;
import java.io.IOException;
import java.util.LinkedList;
import java.util.Collections;
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, k;
            n = fi.nextInt();
            m = fi.nextInt();
            s = fi.nextInt();
            Graph g = new Graph(n);
            for (i = 0; i < m; i++) {
                int a = fi.nextInt();
                int b = fi.nextInt();
                g.addEdge(a, b);
            }
            for (i = 1; i <= n; i++) {
                if (!g.vis[i]) {
                    g.dfs1(i);
                }
            }
            g.reset();
            int cnt = 1;
            Collections.reverse(g.order);
            while (!g.order.isEmpty()) {
                int x = g.order.removeFirst();
                if (!g.vis[x]) {
                    g.dfs2(x, cnt);
                    cnt++;
                }
            }
            cnt--;

            Graph condensed = new Graph(cnt);
            for (i = 1; i <= n; i++) {
                for (int d : g.adj[i]) {
                    if (g.component[d] != g.component[i]) {
                        condensed.addEdge(g.component[i], g.component[d]);
                    }
                }
            }
            condensed.dfs1(g.component[s]);
            int ans = 0;
            for (i = 1; i <= cnt; i++) {
                if (condensed.indegree[i] == 0 && !condensed.vis[i]) {
                    ans++;
                }
            }
            out.println(ans);
        }

    }

    static class Graph {
        int n;
        ArrayList<Integer>[] adj;
        ArrayList<Integer>[] adjR;
        LinkedList<Integer> order;
        boolean[] vis;
        int[] indegree;
        int[] component;

        Graph(int n) {
            this.n = n;
            adj = new ArrayList[n + 1];
            adjR = new ArrayList[n + 1];
            order = new LinkedList<>();
            vis = new boolean[n + 1];
            indegree = new int[n + 1];
            component = new int[n + 1];
            for (int i = 0; i <= n; i++) {
                adj[i] = new ArrayList<>();
                adjR[i] = new ArrayList<>();
            }
        }

        void reset() {
            Arrays.fill(vis, false);
        }

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

        void dfs1(int s) {
            if (vis[s]) return;
            vis[s] = true;
            for (int x : adj[s]) {
                dfs1(x);
            }
            order.add(s);
        }

        void dfs2(int s, int cnt) {
            if (vis[s]) return;
            component[s] = cnt;
            vis[s] = true;
            for (int x : adjR[s]) {
                if (!vis[x])
                    dfs2(x, cnt);
            }
        }

    }

    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);

        }

    }
}

