#include<iostream>
using namespace std;
int main()
{
    int n,a,b,flag=0,x,y,i;
    cin>>n;
    cin>>a>>b;
    for(i=0;i<n-1;i++)
    {
        cin>>x>>y;
        if(x==a && (flag==0 || flag==1))
        {
            flag=1;
        }
        else if(y==b && (flag==0 || flag==2))
        {
            flag=2;
        }
        else
        {
            flag=3;
        }
    }
    if(flag==1 || flag==2)
        cout<<"YES"<<endl;
    else
        cout<<"NO"<<endl;
}