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.
/*
Keep solving problems.
*/

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

public class CFA {
    BufferedReader br;
    PrintWriter out;
    StringTokenizer st;
    boolean eof;
    private static final long MOD = 1000 * 1000 * 1000 + 7;
    private static final int[] dx = {0, -1, 0, 1};
    private static final int[] dy = {1, 0, -1, 0};
    private static final String yes = "Yes";
    private static final String no = "No";

    int n;
    int m;
    int s;
    List<List<Integer>> graph = new ArrayList<>();
    List<List<Integer>> revGraph = new ArrayList<>();
    void solve() throws IOException {
        n = nextInt();
        m = nextInt();
        s = nextInt() - 1;
        for (int i = 0; i < n; i++) {
            graph.add(new ArrayList<>());
            revGraph.add(new ArrayList<>());
        }
        for (int i = 0; i < m; i++) {
            //an edge from u to v
            int u = nextInt() - 1;
            int v = nextInt() - 1;
            graph.get(u).add(v);
            revGraph.get(v).add(u);
        }

        List<List<Integer>> comps = connectedComp();
        int[] ids = new int[n];
        for (int i = 0; i < comps.size(); i++) {
            for (int v : comps.get(i)) {
                ids[v] = i;
            }
        }

        boolean[] vis = new boolean[n];
        dfs(s, vis);
        Set<Integer> cnt = new HashSet<>();
        int[] degree = new int[n];
        for (int i = 0; i < n; i++) {
            for (int nxt : graph.get(i)) {
                if (ids[nxt] != ids[i]) {
                    degree[ids[nxt]]++;
                }
            }
        }

        for (int i = 0; i < n; i++) {
            if (degree[ids[i]] == 0 && ids[i] != ids[s]) {
                cnt.add(ids[i]);
            }
        }

        outln(cnt.size());
    }

    void dfs(int cur, boolean[] vis) {
        if (vis[cur]) {
            return;
        }
        vis[cur] = true;
        for (int nxt : graph.get(cur)) {
            dfs(nxt, vis);
        }
    }

    List<List<Integer>> connectedComp(){
        Stack<Integer> st = new Stack<>();
        boolean[] visited = new boolean[n];
        for (int i = 0; i < n; i++) {
            if (!visited[i]) {
                helper(st, graph, visited, i);
            }
        }

        //System.out.println(st.toString());
        Arrays.fill(visited, false);
        List<List<Integer>> res = new ArrayList<>();
        while(!st.isEmpty()) {
            int v = st.pop();
            if(!visited[v]) {
                Stack<Integer> temp = new Stack<>();
                List<Integer> ls = new ArrayList<>();
                temp.push(v);
                ls.add(v);
                while(!temp.isEmpty()){
                    int u = temp.pop();
                    visited[u] = true;
                    for (int nxt : revGraph.get(u)) {
                        if (!visited[nxt]) {
                            temp.push(nxt);
                            ls.add(nxt);
                        }
                    }
                }
                res.add(ls);
            }
        }
        return res;
    }

    void helper(Stack<Integer> st, List<List<Integer>> graph, boolean[] visited, int cur){
        if(!visited[cur]) {
            visited[cur] = true;
            for (int nxt : graph.get(cur)) {
                helper(st, graph, visited, nxt);
            }

            st.push(cur);
        }
    }

    void shuffle(int[] a) {
        int n = a.length;
        for(int i = 0; i < n; i++) {
            int r = i + (int) (Math.random() * (n - i));
            int tmp = a[i];
            a[i] = a[r];
            a[r] = tmp;
        }
    }

    long gcd(long a, long b) {
        while(a != 0 && b != 0) {
            long c = b;
            b = a % b;
            a = c;
        }
        return a + b;
    }

    private void outln(Object o) {
        out.println(o);
    }
    private void out(Object o) {
        out.print(o);
    }
    private void formatPrint(double val) {
        System.out.format("%.9f%n", val);
    }
    public CFA() throws IOException {
        br = new BufferedReader(new InputStreamReader(System.in));
        out = new PrintWriter(System.out);
        solve();
        out.close();
    }
    public static void main(String[] args) throws IOException {
        new CFA();
    }

    public long[] nextLongArr(int n) throws IOException{
        long[] res = new long[n];
        for(int i = 0; i < n; i++)
            res[i] = nextLong();
        return res;
    }
    public int[] nextIntArr(int n) throws IOException {
        int[] res = new int[n];
        for(int i = 0; i < n; i++)
            res[i] = nextInt();
        return res;
    }
    public String nextToken() {
        while (st == null || !st.hasMoreTokens()) {
            try {
                st = new StringTokenizer(br.readLine());
            } catch (Exception e) {
                eof = true;
                return null;
            }
        }
        return st.nextToken();
    }
    public String nextString() {
        try {
            return br.readLine();
        } catch (IOException e) {
            eof = true;
            return null;
        }
    }
    public int nextInt() throws IOException {
        return Integer.parseInt(nextToken());
    }
    public long nextLong() throws IOException {
        return Long.parseLong(nextToken());
    }
    public double nextDouble() throws IOException {
        return Double.parseDouble(nextToken());
    }
}