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.util.*;
import java.io.*;

public class E490 {
    static ArrayList<Integer> [] adj;
    static ArrayList<Integer> [] rev;
    static int [] post;
    static int c;
    static int [] scc;
    static boolean [] vis;
    static HashSet<Integer> bad = new HashSet<>();
    public static void main(String[] args) {
        MyScanner sc = new MyScanner();
        PrintWriter out = new PrintWriter(new BufferedOutputStream(System.out));
        int n = sc.nextInt(); int m = sc.nextInt(); int s = sc.nextInt();
        adj = new ArrayList[n + 1];
        rev = new ArrayList[n + 1];
        for (int i = 1; i <= n; i++) {
            adj[i] = new ArrayList<>();
            rev[i] = new ArrayList<>();
        }
        for (int i = 0; i < m; i++) {
            int u = sc.nextInt(); int v= sc.nextInt();
            adj[u].add(v);
            rev[v].add(u);
        }
        post = new int[n + 1];
        Arrays.fill(post, -1);
        c = 0;
        vis = new boolean[n + 1];
        for (int i = 1; i <= n; i++) {
            if (!vis[i]) {
                dfs(i, -1);
            }
        }
        vis = new boolean[n + 1];
        scc = new int[n + 1];
        c = 0;
        ArrayList<Integer> process = new ArrayList<>();
        for (int i = 1; i <= n; i++) process.add(i);
        Collections.sort(process, Comparator.comparingInt(x -> -post[x]));
        bad = new HashSet<>();
        for (Integer i: process) {
            if (!vis[i]) {
                dfs2(i, -1);
                ++c;
            }
        }
        int sourceSCCs = c - bad.size();
        int res = sourceSCCs - (bad.contains(scc[s]) ? 0 : 1);
        out.println(res);
        out.close();
    }

    static void dfs(int cur, int par) {
        ++c;
        vis[cur] = true;
        for (Integer next: rev[cur]) {
            if (next != par && !vis[next]) {
                dfs(next, cur);
            }
        }
        post[cur] = c++;
    }

    static void dfs2(int cur, int par) {
        scc[cur] = c;
        vis[cur] = true;
        for (Integer next: adj[cur]) {
            if (next != par && !vis[next]) {
                dfs2(next, cur);
            } else if (next != par) {
                if (scc[next] != c) {
                    bad.add(scc[next]);
                }
            }
        }
    }


    //-----------MyScanner class for faster input----------
    public static class MyScanner {
        BufferedReader br;
        StringTokenizer st;

        public MyScanner() {
            br = new BufferedReader(new InputStreamReader(System.in));
        }

        String next() {
            while (st == null || !st.hasMoreElements()) {
                try {
                    st = new StringTokenizer(br.readLine());
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
            return st.nextToken();
        }

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

        long nextLong() {
            return Long.parseLong(next());
        }

        double nextDouble() {
            return Double.parseDouble(next());
        }

        String nextLine() {
            String str = "";
            try {
                str = br.readLine();
            } catch (IOException e) {
                e.printStackTrace();
            }
            return str;
        }


    }

}