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.IOException;
import java.io.InputStream;
import java.io.PrintWriter;
import java.util.ArrayList;
import java.util.InputMismatchException;
import java.util.Stack;

public class P999E2 {
    private static int cnt;
    private static int cur;
    private static Stack<Vertex> stack;
    private static Vertex[] vertices;

    public static void main(String[] args) {
        InputReader in = new InputReader(System.in);
        PrintWriter pw = new PrintWriter(System.out);

        int n = in.nextInt();
        int m = in.nextInt();
        int s = in.nextInt() - 1;

        stack = new Stack<>();

        vertices = new Vertex[n + n];
        for (int i = 0; i < n + n; ++i) {
            vertices[i] = new Vertex();
            vertices[i].adj = new ArrayList<>();
        }

        for (int i = 0; i < m; ++i) {
            int u = in.nextInt() - 1;
            int v = in.nextInt() - 1;
            vertices[u].adj.add(vertices[v]);
        }

        cur = n;
        for (int i = 0; i < n; ++i) {
            if (vertices[i].dead == 0) vertices[i].dfs();

        }

        for (int i = n; i < cur; ++i) {
            for (Vertex next : vertices[i].adj) {
                Vertex now = next.at;
                if (now == vertices[i]) continue;
                now.indegree++;
            }
        }

        int answer = 0;
        for (int i = n; i < cur; ++i) {
            if (vertices[i].indegree == 0) ++answer;
        }

        if (vertices[s].at.indegree == 0) --answer;

        pw.println(answer);
        pw.close();
    }

    static class InputReader {
        private final InputStream stream;
        private final byte[] buf = new byte[1 << 16];
        private int curChar;
        private int numChars;

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

        public static boolean isWhitespace(int c) {
            return c == 32 || c == 10 || c == 13 || c == 9 || c == -1;
        }

        public int read() {
            if (this.numChars == -1) {
                throw new InputMismatchException();
            } else {
                if (this.curChar >= this.numChars) {
                    this.curChar = 0;

                    try {
                        this.numChars = this.stream.read(this.buf);
                    } catch (IOException var2) {
                        throw new InputMismatchException();
                    }

                    if (this.numChars <= 0) {
                        return -1;
                    }
                }

                return this.buf[this.curChar++];
            }
        }

        public int nextInt() {
            int c;
            for (c = this.read(); this.isSpaceChar(c); ) {
                c = this.read();
            }

            int sgn = 1;
            if (c == 45) {
                sgn = -1;
                c = this.read();
            }

            int res = 0;

            while (c >= 48 && c <= 57) {
                res *= 10;
                res += c - 48;
                c = this.read();
                if (this.isSpaceChar(c)) {
                    return res * sgn;
                }
            }

            throw new InputMismatchException();
        }

        public boolean isSpaceChar(int c) {
            return isWhitespace(c);
        }
    }

    static class Vertex {
        ArrayList<Vertex> adj;
        int indegree;
        int low;
        int num;
        int dead;
        Vertex at;

        void dfs() {
            low = num = ++cnt;
            stack.push(this);
            for (Vertex next : adj) {
                if (next.dead == 1) continue;
                if (next.num > 0) {
                    low = Math.min(low, next.num);
                } else {
                    next.dfs();
                    low = Math.min(low, next.low);
                }
            }

            if (low >= num) {

                while (true) {
                    Vertex now = stack.pop();
                    now.at = vertices[cur];
                    now.dead = 1;
                    now.at.adj.addAll(now.adj);
                    if (now == this) break;
                }
                cur++;
            }
        }

    }
}
