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.BufferedReader;
import java.io.InputStreamReader;
import java.util.ArrayList;
import java.util.HashMap;

public class ReachabilityFromTheCapital {
    private static HashMap<Integer, ArrayList<Integer>> graph;
    private static HashMap<Integer, ArrayList<Integer>> graph2;
    private static HashMap<Integer, Boolean> visited;

    private static int cnt = 0;
    private static HashMap<Integer, Integer> component;
    private static HashMap<Integer, ArrayList<Integer>> componentVector;
    private static HashMap<Integer, Boolean> componentVisited;
    private static ArrayList<Integer> indegree;
    private static ArrayList<Integer> order;

    private static void dfs1(int v) {
        visited.put(v, true);
        for (Integer i: graph.get(v)) {
            if (!visited.get(i)) {
                dfs1(i);
            }
        }
        order.add(v);
    }

    private static void dfs2(int v) {
        visited.put(v, true);
        component.put(v, cnt);
        for (Integer i: graph2.get(v)) {
            if (!visited.get(i)) {
                dfs2(i);
            }
        }
    }

    private static void dfs3(int v) {
        componentVisited.put(v, true);
        for (Integer c: componentVector.get(v)) {
            if (!componentVisited.get(c)){
                dfs3(c);
            }
        }
    }

    public static void main(String[] args) throws Exception{
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));

        String[] inputLine = br.readLine().split(" ");
        int totalCities = Integer.valueOf(inputLine[0]);
        int totalRoads = Integer.valueOf(inputLine[1]);
        int capital = Integer.valueOf(inputLine[2]) - 1;

        graph = new HashMap<>(totalCities);
        graph2 = new HashMap<>(totalCities);
        visited = new HashMap<>(totalCities);
        order = new ArrayList<>(totalCities);
        component = new HashMap<>();
        componentVector = new HashMap<>();
        indegree = new ArrayList<>();

        for (int i = 0; i < totalCities; i++) graph.put(i, new ArrayList<>());
        for (int i = 0; i < totalCities; i++) graph2.put(i, new ArrayList<>());
        for (int i = 0; i < totalCities; i++) visited.put(i, false);

        for (int i = 0; i < totalRoads; i++){
            String[] road = br.readLine().split(" ");
            int startPoint = Integer.valueOf(road[0]) - 1;
            int endPoint = Integer.valueOf(road[1]) - 1;

            graph.get(startPoint).add(endPoint);
            graph2.get(endPoint).add(startPoint);
        }

        for (int i = 0; i < totalCities; i++) if (!visited.get(i)) dfs1(i);
        for (int i = 0; i < totalCities; i++) visited.put(i, false);
        for (int i = 0; i < totalCities; i++) {
            int v = order.get(order.size() - 1 - i);
            if (!visited.get(v)) {
                dfs2(v);
                indegree.add(0);
                cnt++;
            }
        }

        for (int i = 0; i < cnt; i++) componentVector.put(i, new ArrayList<>());
        for (int v = 0; v < totalCities; v++) {
            for (Integer i: graph.get(v)) {
                if (!component.get(v).equals(component.get(i))) {
                    componentVector.get(component.get(v)).add(component.get(i));
                    indegree.set(component.get(i), indegree.get(component.get(i)) + 1);
                }
            }
        }

        componentVisited = new HashMap<>();
        for (int i = 0; i < cnt; i++) componentVisited.put(i, false);
        dfs3(component.get(capital));

        int result = 0;
        for (int i = 0; i < cnt; i++) {
            if (!componentVisited.get(i) && indegree.get(i) == 0) {
                result += 1;
            }
        }

        System.out.println(result);
    }
}
