граф

#include <bits/stdc++.h>
using namespace std;

int n, m, sz, mx, q[200005], a, b, g[200005], ans, pr[200005];
vector <int> x[200005];

int dfs(int v){
	pr[v]=1;
  int k = 0;
  if(v == b)
    return 1;
	for (int i=0; i<(int)x[v].size(); i++){
		if (!pr[x[v][i]]){
			k=max(k, dfs(x[v][i]));
		}
	}
	return k;
}

int main(){
  cin >> n >> m;
	for (int i = 0; i < m; i++){
		cin >> a >> b;
		x[a].push_back(b);
		x[b].push_back(a);
	}
	cin >> a >> b;
	if(dfs(a)){
	  cout << "yes";
	}
	else{
	  cout << "no";
	}
}