dfs

#include<bits/stdc++.h>
using namespace std;
typedef long long ll;
#define fastread() (ios_base:: sync_with_stdio(false),cin.tie(NULL))
ll const N=2e6;
vector<ll>v[N+1];
vector<ll>v1[N+1];

bool vis[N+1];

ll cost[100];

ll level[N+10];

ll level1[N+10];

bool flag,cycle;

ll sub_tree[N+10];

ll n,m,a,b;

void input()
{
    cin>>n>>m;

    ll a,b;

    for(ll i=0; i<m; i++)
    {
        cin>>a>>b;
        v[a].push_back(b);
        v[b].push_back(a);
    }
}

void DFS(ll s)
{
    vis[s]=true;
    for(auto x:v[s])
    {
        if(!vis[x])
        {
            if(x==b)flag=true;
            vis[x]=true;
            DFS(x);
        }
    }
}

int main()
{
    fastread();

    input();
  //ll a,b;
  cin>>a>>b;
    DFS(a);
    if(flag)cout<<"YES"<<endl;
    else cout<<"NO"<<endl;
}
/*
6 6
1 2
1 3
2 4
2 6
3 5
3 4

*/