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.*;
import java.util.*;

public class R490E {

	/*
	4 2 1
	2 4
	3 4
	 */

	static Node[] graph;
	static boolean[] v;
	static boolean[] u;
	static int[] add;
	static int ans;

	public static void main(String[] args) {
		JS scan = new JS();
		PrintWriter out = new PrintWriter(System.out);
		int n = scan.nextInt();
		int m = scan.nextInt();
		int s = scan.nextInt()-1;
		v = new boolean[n];
		graph = new Node[n];
		for(int i = 0; i < n; i++) graph[i] = new Node(i);
		for(int i = 0; i < m; i++) {
			int u = scan.nextInt()-1;
			int v = scan.nextInt()-1;
			graph[u].front.add(v);
			graph[v].back.add(u);
		}
		ans = 0;
		frontDFS(s);
		PriorityQueue<Node> q = new PriorityQueue<Node>();
		for(int i = 0; i < n; i++) {
			if(!v[i]) {
				u = new boolean[n];
				int x = frontDFS2(i);
				q.add(new Node(i, x));
			}
		}
		while(!q.isEmpty()) {
			Node p = q.poll();
			if(!v[p.i]) {
				ans++;
				frontDFS(p.i);
			}
		}
		System.out.println(ans);
	}

	static int frontDFS2(int i) {
		u[i] = true;
		int res = 1;
		for(int j = 0; j < graph[i].front.size(); j++) {
			int to = graph[i].front.get(j);
			if(!u[to]) {
				res += frontDFS2(to);
			}
		}
		return res;
	}

	static int frontDFS(int i) {
		v[i] = true;
		int res = 1;
		for(int j = 0; j < graph[i].front.size(); j++) {
			int to = graph[i].front.get(j);
			if(!v[to]) {
				res += frontDFS(to);
			}
		}
		return res;
	}

	static class Node implements Comparable<Node>{

		int i;
		int cnt;
		ArrayList<Integer> front = new ArrayList<Integer>();
		ArrayList<Integer> back = new ArrayList<Integer>();

		public Node(int i) {
			this.i = i;
		}

		public Node(int i, int c) {
			this.i = i;
			this.cnt = c;
		}

		@Override
		public int compareTo(Node arg0) {
			return arg0.cnt-this.cnt;
		}
	}

	static class JS{
		public int BS = 1<<16;
		public char NC = (char)0;
		byte[] buf = new byte[BS];
		int bId = 0, size = 0;
		char c = NC;
		double num = 1;
		BufferedInputStream in;

		public JS() {
			in = new BufferedInputStream(System.in, BS);
		}

		public JS(String s) throws FileNotFoundException {
			in = new BufferedInputStream(new FileInputStream(new File(s)), BS);
		}

		public char nextChar(){
			while(bId==size) {
				try {
					size = in.read(buf);
				}catch(Exception e) {
					return NC;
				}				
				if(size==-1)return NC;
				bId=0;
			}
			return (char)buf[bId++];
		}

		public int nextInt() {
			return (int)nextLong();
		}

		public long nextLong() {
			num=1;
			boolean neg = false;
			if(c==NC)c=nextChar();
			for(;(c<'0' || c>'9'); c = nextChar()) {
				if(c=='-')neg=true;
			}
			long res = 0;
			for(; c>='0' && c <='9'; c=nextChar()) {
				res = (res<<3)+(res<<1)+c-'0';
				num*=10;
			}
			return neg?-res:res;
		}

		public double nextDouble() {
			double cur = nextLong();
			return c!='.' ? cur:cur+nextLong()/num;
		}

		public String next() {
			StringBuilder res = new StringBuilder();
			while(c<=32)c=nextChar();
			while(c>32) {
				res.append(c);
				c=nextChar();
			}
			return res.toString();
		}

		public String nextLine() {
			StringBuilder res = new StringBuilder();
			while(c<=32)c=nextChar();
			while(c!='\n') {
				res.append(c);
				c=nextChar();
			}
			return res.toString();
		}

		public boolean hasNext() {
			if(c>32)return true;
			while(true) {
				c=nextChar();
				if(c==NC)return false;
				else if(c>32)return true;
			}
		}
	}
}
