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.
/**
 * Created by sky on 26/7/18.
 * www.github.com/aakashjaiswal1
 * aakashjaiswal@hotmail.co.in
 * aakashjaiswal.in@gmail.com
 * people die if they are killed
 */
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.util.*;

public class defawwult_t {
    public static void main(String[] args) {
        in = new FastReader();
        int n=ni();
        int m=ni();
        int source=ni()-1;
        Graph g=new Graph(n);
        for (int i=0;i<m;i++){
            int x=ni()-1;
            int y=ni()-1;
            g.addDir(x,y);
        }
        Stack<Integer> s=new Stack<>();
        boolean[] visited=new boolean[n];
        for (int i=0;i<n;i++){
            g.scc_helper_stack(s,visited,i);
        }
       // System.out.println(s);
        Graph gc=g.compliment();
        visited=new boolean[n];
        ArrayList<ArrayList<Integer>> master=new ArrayList<>();
        while (s.size()>0){
            ArrayList<Integer> contri=new ArrayList<>();
            int ele=s.pop();
            if (visited[ele])continue;
            Stack<Integer> stack=new Stack<>();
            stack.add(ele);
            while (stack.size()>0){
                int item=stack.pop();
                contri.add(item);
                visited[item]=true;
                ArrayList<Integer> neigh=gc.al_array[item];
                for (int pos=0;pos<neigh.size();pos++){
                    int ne=neigh.get(pos);
                    if (!visited[ne])stack.add(ne);
                }
            }
            master.add(contri);
        }
        int[] locator=new int[n];
        for (int i=0;i<master.size();i++){
            ArrayList<Integer> al=master.get(i);
            for (int j=0;j<al.size();j++){
                int node=al.get(j);
                locator[node]=i;
            }
        }
        int[] inderee=new int[master.size()];
        for (int i=0;i<n;i++){
            ArrayList<Integer> al=g.al_array[i];
            for (int j=0;j<al.size()  ;j++){
                int node=al.get(j);
                if (locator[i]!=locator[node])
                inderee[locator[node]]++;
            }
        }
        long ans=0;
        for (int i=0;i<inderee.length;i++){
            if (i==locator[source])continue;
            if (inderee[i]==0)ans++;
        }
        System.out.println(ans);

    }
//    static void helper(ArrayList<ArrayList<Integer>> master,int node,boolean[] visited,Graph gc){
//        if (visited[node])return;
//
//    }

    public static long binarySearch(long low, long high) {
        while (high - low > 1) {
            long mid = (high - low)/2 + low;
            //System.out.println(mid);
            if (works(mid)) {
                high = mid;
            } else {
                low = mid;
            }
        }
        return (works(low) ? low : high);
    }
    static class Graph{
        ArrayList<Integer> al_array[];
        int nodes;
        Graph(int no){
            this.nodes=no;
            this.al_array=new ArrayList[no];
            for (int i=0;i<no;i++){
                al_array[i]=new ArrayList<>();
            }
        }
        void addDir(int i,int j){
            this.al_array[i].add(j);
        }
        void addUndir(int i,int j){
            this.al_array[i].add(j);
            this.al_array[j].add(i);
        }
       void scc_helper_stack(Stack<Integer> s,boolean[] visited,int node){
          if (visited[node])return;
          visited[node]=true;
          ArrayList<Integer> neigh=this.al_array[node];
          for (int i=0;i<neigh.size();i++){
              int child=neigh.get(i);
              if (!visited[child]){
                  scc_helper_stack(s,visited,child);
              }
          }
          s.add(node);
        }
        Graph compliment(){
            Graph com=new Graph(this.nodes);
            for (int i=0;i<this.nodes;i++){
                ArrayList<Integer> al=this.al_array[i];
                for (int j=0;j<al.size();j++){
                    int node=al.get(j);
                    com.addDir(node,i);
                }
            }
            return com;
        }

    }
    static long fast_exp_with_mod(long base, long exp) {
        long MOD=1000000000+7;
        long res=1;
        while(exp>0) {
            if(exp%2==1) res=(res*base)%MOD;
            base=(base*base)%MOD;
            exp/=2;
        }
        return res%MOD;
    }
    public static long gcd(long a, long b)
    {
        if (a == 0)
            return b;
        return gcd(b%a, a);
    }
    static class my_no{
        long num;
        long denom;

        @Override
        public String toString() {
            if (denom<0){
                this.num=-this.num;
                this.denom=-this.denom;
            }
            if (num==0)return "0";
            return (num+"/"+denom);
        }

        my_no(int no){
            this.num=no;
            this.denom=1;
        }
        my_no(long num,long denom){
            this.num=num;
            this.denom=denom;
        }

        my_no multiply(my_no obj){
            long num1=obj.num;
            long denom1=obj.denom;
            long n=num1*num;
            long d=denom1*denom;
            long gcd=gcd(n,d);
            n/=gcd;
            d/=gcd;
            return new my_no(n,d);

        }
//        my_no multiply(my_no obj){
//            long num1=obj.num;
//            long denom1=obj.denom;
//            long num2=this.num;
//            long denom2=this.denom;
//
//        }

        my_no multiply(int no){
            long n=num*no;
            long d=denom;
            long gcd=gcd(n,d);
            n/=gcd;
            d/=gcd;
            return new my_no(n,d);

        }
    }
    static void memset(int[][] arr,int val){
        for (int i=0;i<arr.length;i++){
            for (int j=0;j<arr[i].length;j++){
                arr[i][j]=val;
            }
        }
    }
    static void memset(int[] arr,int val){
        for (int i=0;i<arr.length;i++){
            arr[i]=val;
        }
    }


    static void memset(long[][] arr,long val){
        for (int i=0;i<arr.length;i++){
            for (int j=0;j<arr[i].length;j++){
                arr[i][j]=val;
            }
        }
    }
    static void memset(long[] arr,long val){
        for (int i=0;i<arr.length;i++){
            arr[i]=val;
        }
    }
    static private boolean works(long test){
        return true;
    }


    static void reverse(char[] arr ,int i,int j){
        if (i==j)
            return;
        while (i<j){
            char temp=arr[i];
            arr[i]=arr[j];
            arr[j]=temp;
            ++i;
            --j;
        }
    }
    static int[]  takeIntegerArrayInput(int no){
        int[] arr=new int[no];
        for (int i=0;i<no;++i){
            arr[i]=ni();
        }
        return arr;
    }
    static long fast_Multiply(long no , long pow){
        long result=1;
        while (pow>0){
            if ((pow&1)==1){
                result=result*no;
            }
            no=no*no;
            pow>>=1;
        }
        return result;
    }

    static long[]  takeLongArrayInput(int no){
        long[] arr=new long[no];
        for (int i=0;i<no;++i){
            arr[i]=ni();
        }
        return arr;
    }
    static final long MOD = (long)1e9+7;
    static FastReader in;


    static void p(Object o){
        System.out.print(o);
    }

    static void pn(Object o){
        System.out.println(o);
    }

    static String n(){
        return in.next();
    }

    static String nln(){
        return in.nextLine();
    }

    static int ni(){
        return Integer.parseInt(in.next());
    }

    static int[] ia(int N){
        int[] a = new int[N];
        for(int i = 0; i<N; i++)a[i] = ni();
        return a;
    }

    static long[] la(int N){
        long[] a = new long[N];
        for(int i = 0; i<N; i++)a[i] = nl();
        return a;
    }

    static long nl(){
        return Long.parseLong(in.next());
    }

    static double nd(){
        return Double.parseDouble(in.next());
    }

    static class FastReader{
        BufferedReader br;
        StringTokenizer st;
        public FastReader(){
            br = new BufferedReader(new InputStreamReader(System.in));
        }

        String next(){
            while (st == null || !st.hasMoreElements()){
                try{
                    st = new StringTokenizer(br.readLine());
                }catch (IOException e){
                    e.printStackTrace();
                }
            }
            return st.nextToken();
        }

        String nextLine(){
            String str = "";
            try{
                str = br.readLine();
            }catch (IOException e){
                e.printStackTrace();
            }
            return str;
        }
    }
    static void println(String[] arr){
        for (int i=0;i<arr.length;++i){
            System.out.println(arr[i]);
        }
    }

}

