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.FileInputStream;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.OutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.PrintWriter;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Comparator;
import java.util.HashMap;
import java.util.LinkedList;
import java.util.List;
import java.util.Map;
import java.util.StringTokenizer;
import java.io.BufferedReader;
import java.io.InputStreamReader;


public class Main
{
	public static void main(String[] args) throws FileNotFoundException
	{
		InputStream inputStream = System.in;//new FileInputStream("input.txt");
		OutputStream outputStream = System.out;//new FileOutputStream("output.txt");
		InputReader in = new InputReader(inputStream);
		PrintWriter out = new PrintWriter(outputStream);
		//////////////////////////////////////////////////////////////////////////////
		TaskE solver = new TaskE();
		solver.solve(in, out);
		//////////////////////////////////////////////////////////////////////////////
		out.close();
	}

	static class Pair
	{
		int first;
		int second;

		public Pair(int a, int b)
		{
			this.first = a;
			this.second = b;
		}
	}

	// class to define user defined comparator
	static class Compare
	{
	    void compare(Pair arr[], int n)
	    {
	        Arrays.sort(arr, new Comparator<Pair>() {
	            @Override public int compare(Pair p1, Pair p2)
	            {
	            	if(p1 != null && p2 != null)
	            		return p1.first - p2.first;
	            	return 0;
	            }
	        });
	    }
	}

	static class TaskE
	{
		int n, m, s, u, v, cnt=0;
		LinkedList<Integer>[] adjList;
		boolean[] visited, visited2;

		public void solve(InputReader in, PrintWriter out)
		{
			//// Reading input - Init - forming graph
			n = in.nextInt();
			m = in.nextInt();
			s = in.nextInt();

			visited = new boolean[n];
			adjList = new LinkedList[n];
			for(int i=0; i<n; i++)
				adjList[i] = new LinkedList<Integer>();

			for(int i=0; i<m; i++)
			{
				u = in.nextInt();
				v = in.nextInt();

				if(adjList[u-1] == null)
					adjList[u-1] = new LinkedList<Integer>();
				adjList[u-1].add(v-1);
			}

			//// First Call
			dfs(s-1);

			//// Un-Reachables Calls
			int indx=0;
			Pair[] reachables = new Pair[n];
			for(int i=0; i<n; i++)
			{
				if(!visited[i])
				{
					cnt = 0;
					visited2 = new boolean[n];
					dfs2(i);
					reachables[indx++] = new Pair(cnt, i);
				}
			}
			Compare compObj = new Compare();
			compObj.compare(reachables, indx);

			int ans = 0;
			for(int j=indx-1; j>=0; j--)
			{
				if(!visited[reachables[j].second])
				{
					dfs(reachables[j].second);
					ans++;
				}
			}
			out.println(ans);
		}

		private void dfs(int node)
		{
			visited[node] = true;
			for(int i = 0; i < adjList[node].size(); i++)
			{
				if(!visited[adjList[node].get(i)])
					dfs(adjList[node].get(i));
			}
		}

		private void dfs2(int node)
		{
			visited2[node] = true;
			cnt++;
			for(int i = 0; i < adjList[node].size(); i++)
			{
				if(!visited[adjList[node].get(i)] && !visited2[adjList[node].get(i)])
					dfs2(adjList[node].get(i));
			}
		}
	}

	static class InputReader
	{
		public BufferedReader reader;
		public StringTokenizer tokenizer;

		public InputReader(InputStream stream)
		{
			reader = new  BufferedReader(new InputStreamReader(stream));
			tokenizer = null;
		}

		public String next()
		{
			while(tokenizer == null || !tokenizer.hasMoreTokens())
			{
				try
				{
					tokenizer = new StringTokenizer(reader.readLine());
				}
				catch(IOException e)
				{
					e.printStackTrace();
				}
			}
			return tokenizer.nextToken();
		}

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

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

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


}
