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.*;
import java.lang.*;
import java.util.HashMap;
public class templ implements Runnable {
    public static ArrayList<Integer> g[]=new ArrayList[1000000];
    public static int vis[]=new int[1000000];
    public static int vis1[]=new int[1000000];
    public static int k=0;
    void dfs(int n)
    {
        vis[n]=1;
        for(int i=0;i<g[n].size();i++)
        {
            int u=g[n].get(i);
            if(vis[u]==0)
                dfs(u);
        }
    }
    void dfs1(int n)
    {
        vis1[n]=1;
        if(vis[n]==0)
            k++;
        for(int i=0;i<g[n].size();i++)
        {
            int u=g[n].get(i);
            if(vis1[u]==0)
                dfs1(u);
        }
    }
    int binarySearch(int arr[], int l, int r, int x)
    {
        if (r >= l)
        {
            int mid = l + (r - l)/2;
            if (arr[mid] == x)
                return mid;
            if (arr[mid] > x)
                return binarySearch(arr, l, mid-1, x);
            return binarySearch(arr, mid+1, r, x);
        }
        return -1;
    }
    void merge1(int arr[], int l, int m, int r)
    {
        int n1 = m - l + 1;
        int n2 = r - m;
        int L[] = new int [n1];
        int R[] = new int [n2];
        for (int i=0; i<n1; ++i)
            L[i] = arr[l + i];
        for (int j=0; j<n2; ++j)
            R[j] = arr[m + 1+ j];
        int i = 0, j = 0;
        int k = l;
        while (i < n1 && j < n2)
        {
            if (L[i]<=R[j])
            {
                arr[k] = L[i];
                i++;
            }
            else
            {
                arr[k] = R[j];
                j++;
            }
            k++;
        }
        while (i < n1)
        {
            arr[k] = L[i];
            i++;
            k++;
        }
        while (j < n2)
        {
            arr[k] = R[j];
            j++;
            k++;
        }
    }
    void sort1(int arr[], int l, int r)
    {
        if (l < r)
        {
            int m = (l+r)/2;
            sort1(arr, l, m);
            sort1(arr , m+1, r);
            merge1(arr, l, m, r);
        }
    }
    void merge3(int arr[],int arr1[],long arr2[], int l, int m, int r)
    {
        int n1 = m - l + 1;
        int n2 = r - m;
        int L[] = new int [n1];
        int R[] = new int [n2];
        int L1[]=new int[n1];
        int R1[]=new int[n2];
        long L2[]=new long[n1];
        long R2[]=new long[n2];
        //long L3[]=new long[n1];
        //long R3[]=new long[n2];
        for (int i=0; i<n1; ++i)
        {
            L[i] = arr[l + i];
            L1[i]=arr1[l+i];
            L2[i]=arr2[l+i];
            //L3[i]=arr3[l+i];
        }
        for (int j=0; j<n2; ++j)
        {
            R[j] = arr[m + 1+ j];
            R1[j]=arr1[m+1+j];
            R2[j]=arr2[m+1+j];
            //R3[j]=arr3[m+1+j];
        }
        int i = 0, j = 0;
        int k = l;
        while (i < n1 && j < n2)
        {
            if (L[i] <= R[j])
            {
                arr[k] = L[i];
                arr1[k]=L1[i];
                arr2[k]=L2[i];
                //arr3[k]=L3[i];
                i++;
            }
            else
            {
                arr[k] = R[j];
                arr1[k]=R1[j];
                arr2[k]=R2[j];
                //arr3[k]=R3[j];
                j++;
            }
            k++;
        }
        while (i < n1)
        {
            arr[k] = L[i];
            arr1[k]=L1[i];
            arr2[k]=L2[i];
            //arr3[k]=L3[i];
            i++;
            k++;
        }
        while (j < n2)
        {
            arr[k] = R[j];
            arr1[k]=R1[j];
            arr2[k]=R2[j];
            //arr3[k]=R3[j];
            j++;
            k++;
        }
    }
    void sort3(int arr[],int arr1[],long arr2[], int l, int r)
    {
        if (l < r)
        {
            int m = (l+r)/2;
            sort3(arr,arr1,arr2, l, m);
            sort3(arr ,arr1,arr2, m+1, r);
            merge3(arr,arr1,arr2,l, m, r);
        }
    }
    void merge2(int arr[],int arr1[],int l, int m, int r)
    {
        int n1 = m - l + 1;
        int n2 = r - m;
        int L[] = new int [n1];
        int R[] = new int [n2];
        int L1[]=new int[n1];
        int R1[]=new int[n2];
        for (int i=0; i<n1; ++i)
        {
            L[i] = arr[l + i];
            L1[i]=arr1[l+i];
        }
        for (int j=0; j<n2; ++j)
        {
            R[j] = arr[m + 1+ j];
            R1[j]=arr1[m+1+j];
        }
        int i = 0, j = 0;
        int k = l;
        while (i < n1 && j < n2)
        {
            if (L[i] <= R[j])
            {
                arr[k] = L[i];
                arr1[k]=L1[i];
                i++;
            }
            else
            {
                arr[k] = R[j];
                arr1[k]=R1[j];
                j++;
            }
            k++;
        }
        while (i < n1)
        {
            arr[k] = L[i];
            arr1[k]=L1[i];
            i++;
            k++;
        }
        while (j < n2)
        {
            arr[k] = R[j];
            arr1[k]=R1[j];
            j++;
            k++;
        }
    }
    void sort2(int arr[],int arr1[],int l, int r)
    {
        if (l < r)
        {
            int m = (l+r)/2;
            sort2(arr,arr1, l, m);
            sort2(arr ,arr1, m+1, r);
            merge2(arr,arr1,l, m, r);
        }
    }
    void merge4(int arr[],int arr1[],int arr2[],int arr3[], int l, int m, int r)
    {
        int n1 = m - l + 1;
        int n2 = r - m;
        int L[] = new int [n1];
        int R[] = new int [n2];
        int L1[]=new int[n1];
        int R1[]=new int[n2];
        int L2[]=new int[n1];
        int R2[]=new int[n2];
        int L3[]=new int[n1];
        int R3[]=new int[n2];
        for (int i=0; i<n1; ++i)
        {
            L[i] = arr[l + i];
            L1[i]=arr1[l+i];
            L2[i]=arr2[l+i];
            L3[i]=arr3[l+i];
        }
        for (int j=0; j<n2; ++j)
        {
            R[j] = arr[m + 1+ j];
            R1[j]=arr1[m+1+j];
            R2[j]=arr2[m+1+j];
            R3[j]=arr3[m+1+j];
        }
        int i = 0, j = 0;
        int k = l;
        while (i < n1 && j < n2)
        {
            if (L[i] <= R[j])
            {
                arr[k] = L[i];
                arr1[k]=L1[i];
                arr2[k]=L2[i];
                arr3[k]=L3[i];
                i++;
            }
            else
            {
                arr[k] = R[j];
                arr1[k]=R1[j];
                arr2[k]=R2[j];
                arr3[k]=R3[j];
                j++;
            }
            k++;
        }
        while (i < n1)
        {
            arr[k] = L[i];
            arr1[k]=L1[i];
            arr2[k]=L2[i];
            arr3[k]=L3[i];
            i++;
            k++;
        }
        while (j < n2)
        {
            arr[k] = R[j];
            arr1[k]=R1[j];
            arr2[k]=R2[j];
            arr3[k]=R3[j];
            j++;
            k++;
        }
    }
    void sort4(int arr[],int arr1[],int arr2[],int arr3[], int l, int r)
    {
        if (l < r)
        {
            int m = (l+r)/2;
            sort4(arr,arr1,arr2,arr3, l, m);
            sort4(arr ,arr1,arr2,arr3, m+1, r);
            merge4(arr,arr1,arr2,arr3,l, m, r);
        }
    }
    public int justsmall(int a[],int l,int r,int x)
    {
        int p=-1;
        while(l<=r)
        {
            int mid=(l+r)/2;
            if(a[mid]<=x)
            {
                p=mid;
                l=mid+1;
            }
            else
                r=mid-1;
        }
        return p;
    }
    public int justlarge(int a[],int l,int r,int x)
    {
        int p=0;
        while(l<=r)
        {
            int mid=(l+r)/2;
            if(a[mid]<=x)
            {
                l=mid+1;
            }
            else
            {
                p=a[mid];
                r = mid - 1;
            }
        }
        return p;
    }
    long gcd(long x,long y)
    {
        if(x%y==0)
            return y;
        else
            return(gcd(y,x%y));
    }
    public static void main(String args[])throws Exception
    {
        new Thread(null,new templ(),"templ",1<<26).start();
    }
    public void run() {
        try
        {
            InputReader in = new InputReader(System.in);
            PrintWriter out = new PrintWriter(System.out);
            templ ob=new templ();
            int n=in.ni();
            int m=in.ni();
            int s=in.ni();
            for(int i=1;i<=n;i++)
                g[i]=new ArrayList();
            for(int i=1;i<=m;i++)
            {
                int u=in.ni();
                int v=in.ni();
                g[u].add(v);
            }
            dfs(s);
            int p[]=new int[10000];
            int val[]=new int[10000];
            int o=0;
            for(int i=1;i<=n;i++)
            {
                if(vis[i]==0)
                {
                    for(int j=1;j<=n;j++)
                        vis1[j]=0;
                    k=0;
                    dfs1(i);
                    p[o]=i;
                    val[o]=k;
                    o++;
                }
            }
            ob.sort2(val,p,0,o-1);
            int ans=0;
            for(int i=o-1;i>=0;i--)
            {
                if(vis[p[i]]==0)
                {
                    ans++;
                    dfs(p[i]);
                }
            }
            out.println(ans);
            out.close();
        }
        catch(Exception e){
            return;
        }
    }
    static class InputReader {

        private final InputStream stream;
        private final byte[] buf = new byte[8192];
        private int curChar, snumChars;

        public InputReader(InputStream stream) {
            this.stream = stream;
        }

        public int read() {
            if (snumChars == -1)
                throw new InputMismatchException();
            if (curChar >= snumChars) {
                curChar = 0;
                try {
                    snumChars = stream.read(buf);
                } catch (IOException e) {
                    throw new InputMismatchException();
                }
                if (snumChars <= 0)
                    return -1;
            }
            return buf[curChar++];
        }

        public int ni() {
            int c = read();
            while (isSpaceChar(c)) {
                c = read();
            }
            int sgn = 1;
            if (c == '-') {
                sgn = -1;
                c = read();
            }
            int res = 0;
            do {
                res *= 10;
                res += c - '0';
                c = read();
            } while (!isSpaceChar(c));
            return res * sgn;
        }

        public long nl() {
            int c = read();
            while (isSpaceChar(c)) {
                c = read();
            }
            int sgn = 1;
            if (c == '-') {
                sgn = -1;
                c = read();
            }
            long res = 0;
            do {
                res *= 10;
                res += c - '0';
                c = read();
            } while (!isSpaceChar(c));
            return res * sgn;
        }

        public int[] nextIntArray(int n) {
            int a[] = new int[n];
            for (int i = 0; i < n; i++) {
                a[i] = ni();
            }
            return a;
        }

        public String readString() {
            int c = read();
            while (isSpaceChar(c)) {
                c = read();
            }
            StringBuilder res = new StringBuilder();
            do {
                res.appendCodePoint(c);
                c = read();
            } while (!isSpaceChar(c));
            return res.toString();
        }

        public String nextLine() {
            int c = read();
            while (isSpaceChar(c))
                c = read();
            StringBuilder res = new StringBuilder();
            do {
                res.appendCodePoint(c);
                c = read();
            } while (!isEndOfLine(c));
            return res.toString();
        }

        public boolean isSpaceChar(int c) {
            return c == ' ' || c == '\n' || c == '\r' || c == '\t' || c == -1;
        }

        private boolean isEndOfLine(int c) {
            return c == '\n' || c == '\r' || c == -1;
        }

    }
}