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.IOException;
import java.io.InputStreamReader;
import java.io.PrintWriter;
import java.util.ArrayDeque;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collections;
import java.util.PriorityQueue;
import java.util.Random;
import java.util.StringTokenizer;

public class Solution{
	
	
	static int n, m, s;
	static ArrayList<Integer>[] g, rg;
	static boolean[] visited;
	static ArrayList<Integer> order;
	static int[] comp;           // stores the component of the condensed graph
	static int cnt = 0;
	static int[] indeg;
	
	
    public static void main(String[] args) throws IOException {
    	
		
    	FastScanner fs = new FastScanner();
    	PrintWriter out = new PrintWriter(System.out);
    		
    	int tt = 1;
    	while(tt-->0) {
    		
    		n = fs.nextInt();
    		m = fs.nextInt();
    		s = fs.nextInt()-1;
    		
    		g = new ArrayList[n];
    		rg = new ArrayList[n];
    		
    		for(int i=0;i<n;i++) {
    			g[i] = new ArrayList<Integer>();
    			rg[i] = new ArrayList<Integer>();
    		}
    		
    		visited = new boolean[n];
    		comp = new int[n];
    		order = new ArrayList<Integer>();
    		
    		for(int i=0;i<m;i++) {
    			int u = fs.nextInt()-1, v = fs.nextInt()-1;
    			g[u].add(v);
    			rg[v].add(u);
    		}
    		
    		for(int i=0;i<n;i++) {
    			if(!visited[i]) {
    				dfs1(i);
    			}
    		}
    		
    		Collections.reverse(order);
    		
    		Arrays.fill(comp, -1);
    		
    		for(int i=0;i<n;i++) {
    			if(comp[order.get(i)]==-1) {
    				dfs2(order.get(i));
    				cnt++;
    			}
    		}
    		
    		indeg = new int[n];
    		
    		for(int v=0;v<n;v++) {
    			for(int u: g[v]) {
    				if(comp[v]!=comp[u]) {
    					indeg[comp[u]]++;
    				}
    			}
    		}
    		
    		int ans = 0;
    		
    		for(int i=0;i<cnt;i++) {
    			if(indeg[i]==0 && i!=comp[s]) {
    				ans++;
    			}
    		}
    		
    		out.println(ans);
    		
    		
    		
    		
    		
    		
    		
    		
    		
    		
    	}
    	
    	out.close();
    		
    }
    
    
    static void dfs1(int v) {
    	visited[v] = true;
    	for(int u: g[v]) {
    		if(!visited[u]) {
    			dfs1(u);
    		}
    	}
    	order.add(v);
    }
    
    
    static void dfs2(int v) {
    	comp[v] = cnt;
    	for(int u: rg[v]) {
    		if(comp[u]==-1) {
    			dfs2(u);
    		}
    	}
    }
    
    
    
    static final Random random=new Random();
    
    static <T> void shuffle(T[] arr) {
    	int n = arr.length;
    	for(int i=0;i<n;i++	) {
    		int k = random.nextInt(n);
    		T temp = arr[k]; arr[k] = arr[i]; arr[i] = temp;
    	}
    }
    
    	
    static void ruffleSort(int[] a) {
    	int n=a.length;//shuffle, then sort 
    	for (int i=0; i<n; i++) {
    		int oi=random.nextInt(n); int temp=a[oi];
    		a[oi]=a[i]; a[i]=temp;
    	}
    	Arrays.sort(a);
    }
    
    static void ruffleSort(long[] a) {
    	int n=a.length;//shuffle, then sort 
    	for (int i=0; i<n; i++) {
    		int oi=random.nextInt(n); long temp=a[oi];
    		a[oi]=a[i]; a[i]=temp;
    	}
    	Arrays.sort(a);
    }
   
  
    
    static void reverse(int[] arr, int l, int r) {
    	for(int i=l;i<l+(r-l)/2;i++){
    		int temp = arr[i]; arr[i] = arr[r-i+l-1]; arr[r-i+l-1] = temp;
    	}
    }
    
    static void reverse(long[] arr, int l, int r) {
    	for(int i=l;i<l+(r-l)/2;i++){
    		long temp = arr[i]; arr[i] = arr[r-i+l-1]; arr[r-i+l-1] = temp;
    	}
    }
    
    
    static <T> void reverse(T[] arr, int l, int r) {
    	for(int i=l;i<l+(r-l)/2;i++) {
    		T temp = arr[i]; arr[i] = arr[r-i+l-1]; arr[r-i+l-1] = temp;
    	}
    }
    	
    	
    static class FastScanner{
    	BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
    	StringTokenizer st = new StringTokenizer("");
     
    	public String next(){
    		while(!st.hasMoreElements()){
    			try{
    				st = new StringTokenizer(br.readLine());
    			} catch(IOException e){
    				e.printStackTrace();
    			}
    		}
    		return st.nextToken();
    	}
    		
    	public String nextLine() throws IOException {
    		return br.readLine();
    	}
    		
    	public int nextInt(){
    		return Integer.parseInt(next());
    	}
     
    	public int[] readArray(int n){
    		int[] a = new int[n];
    		for(int i=0;i<n;i++)
    			a[i] = nextInt();
    		return a;
    	}
    		
    	public long nextLong() {
    		return Long.parseLong(next());
    	}
    		
    	public char nextChar() {
    		return next().toCharArray()[0];
    	}
    }
   	
}
