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.Scanner;
import java.util.Stack;
import java.util.ArrayList;

/**
 * Built using CHelper plug-in
 * Actual solution is at the top
 *
 * @author xuanquang1999
 */
public class Main {
    public static void main(String[] args) {
        InputStream inputStream = System.in;
        OutputStream outputStream = System.out;
        Scanner in = new Scanner(inputStream);
        PrintWriter out = new PrintWriter(outputStream);
        TaskE solver = new TaskE();
        solver.solve(1, in, out);
        out.close();
    }

    static class TaskE {
        public static int n;
        public static int id;
        public static int dfsCnt;
        public static int num[];
        public static int low[];
        public static int comp[];
        public static int degNew[];
        public static ArrayList<Integer> graph[];
        public static boolean avail[];
        public static Stack<Integer> st;

        public void DFS(int u) {
            st.push(u);
            low[u] = num[u] = ++dfsCnt;
            for (int v : graph[u]) {
                if (!avail[v])
                    continue;
                if (num[v] == 0) {
                    DFS(v);
                    low[u] = Math.min(low[u], low[v]);
                } else
                    low[u] = Math.min(low[u], num[v]);
            }

            if (low[u] == num[u]) {
                int v;
                do {
                    v = st.pop();
                    comp[v] = id;
                    avail[v] = false;
                } while (v != u);
                ++id;
            }
        }

        public void solve(int testNumber, Scanner in, PrintWriter out) {
            n = in.nextInt();
            int m = in.nextInt(), s = in.nextInt();
            --s;
            graph = new ArrayList[n];
            for (int u = 0; u < n; ++u)
                graph[u] = new ArrayList<>();

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

            num = new int[n];
            low = new int[n];
            comp = new int[n];
            avail = new boolean[n];
            for (int u = 0; u < n; ++u)
                avail[u] = true;
            id = dfsCnt = 0;
            st = new Stack<>();

            for (int u = 0; u < n; ++u)
                if (avail[u]) DFS(u);

            degNew = new int[id];
            for (int u = 0; u < n; ++u)
                for (int v : graph[u]) 
                    if (comp[u] != comp[v]) ++degNew[comp[v]];

            int ans = 0;
            for (int i = 0; i < id; ++i)
                if (degNew[i] == 0) ++ans;
            if (degNew[comp[s]] == 0) --ans;
            out.println(ans);
        }

    }
}

