#include<bits/stdc++.h>
using namespace std;
#define ioio ios::sync_with_stdio(false);cin.tie(0);cout.tie(0);
#define endl "\n"
#define debug(x) cout<<#x<<":"<<x<<endl;
#define P pair
#define P1 first
#define P2 second
#define u_map unordered_map
#define p_queue priority_queue
typedef long long ll;
const double eps = 1e-6;
const int mod = 1e9 + 7;
const int INF = 0x3f3f3f3f;
const int N = 1e5+ 7;
int dx[] = {1, 0, -1, 0}, dy[] = {0, -1, 0, 1};
/*-------------------------------------------------*/

int n,m;
int fa[N];
int cnt[N];

int fin(int x){
	if(x!=fa[x])
		fa[x]=fin(fa[x]);
	return fa[x];
}
void mer(int x,int y){
	x=fin(x),y=fin(y);
	if(x==y)return ;
	fa[x]=y;
	cnt[y]+=cnt[x];
}
void slove(){
	cin>>n>>m;
	for(int i=1;i<=n;i++){
		fa[i]=i;
		cnt[i]=1;
	}
	int x,y;
	for(int i=1;i<=m;i++){
		cin>>x>>y;
		mer(x,y);
	}
	cin>>x;
	cout<<cnt[fin(x)]<<endl;
}
int main(){
	ioio
	int t=1;
	//cin>>t;
	while(t--)
		slove();
	return 0;
}