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.InputStream;
import java.io.InputStreamReader;
import java.io.BufferedReader;
import java.io.OutputStream;
import java.io.PrintWriter;
import java.io.IOException;
import java.util.*;


public final class Main11 {
    public static void main(String[] args) {
        InputStream inputStream = System.in;
        OutputStream outputStream = System.out;
        InputReader in = new InputReader(inputStream);
        PrintWriter out = new PrintWriter(outputStream);
        TaskA solver = new TaskA();
        int t = 1;
        while(t-- > 0) {
            solver.solve(t, in, out);
        }
        out.close();
    }
}


class TaskA {

    private ArrayList<Integer> topoSort(ArrayList<ArrayList<Integer>> graph, int N, int source) {
        Stack<Integer> stack = new Stack<>();
        HashSet<Integer> visited = new HashSet<>();
        for (int i = 0; i < N; i++) {
            int node = i == 0? source: i == source? 0: i;
            if (!visited.contains(node)) {
                dfs(graph, node, stack, visited);
            }
        }
        ArrayList<Integer> result = new ArrayList<>();
        while (!stack.isEmpty()) {
            result.add(stack.pop());
        }
        return result;
    }

    private void dfs(ArrayList<ArrayList<Integer>> graph, int node, Stack<Integer> stack, HashSet<Integer> visited) {
        visited.add(node);
        for (int child: graph.get(node)) {
            if (!visited.contains(child)) {
                dfs(graph, child, stack, visited);
            }
        }
        stack.push(node);
    }



    public void solve(int testNumber, InputReader in, PrintWriter out) {
        int n = in.nextInt();
        int m = in.nextInt();
        int source = in.nextInt();
        source--;
        ArrayList<ArrayList<Integer>> graph = new ArrayList<>();
        for (int i = 0; i < n; i++)
            graph.add(new ArrayList<>());
        for (int i = 0; i < m; i++) {
            int a = in.nextInt();
            int b = in.nextInt();
            a--;
            b--;
            graph.get(a).add(b);
        }
        ArrayList<Integer> nodes = topoSort(graph, n, source);
        HashSet<Integer> visited = new HashSet<>();
        int result = 0;
        for (int node: nodes) {
            if (!visited.contains(node)) {
                dfs(graph, node, new Stack<>(), visited);
                if (node != source) 
                    result++;
            }
        }
        out.println(result);
    }
}

class InputReader {
    public BufferedReader reader;
    public StringTokenizer tokenizer;

    public InputReader(InputStream stream) {
        reader = new BufferedReader(new InputStreamReader(stream), 32768);
        tokenizer = null;
    }

    public String next() {
        while (tokenizer == null || !tokenizer.hasMoreTokens()) {
            try {
                tokenizer = new StringTokenizer(reader.readLine());
            } catch (IOException e) {
                throw new RuntimeException(e);
            }
        }
        return tokenizer.nextToken();
    }

    public int nextInt() {
        return Integer.parseInt(next());
    }
}

