#include <cmath>
#include <cstdio>
#include <vector>
#include <iostream>
#include <algorithm>
using namespace std;


int main() {
    /* Enter your code here. Read input from STDIN. Print output to STDOUT */   
    int n;
    cin>>n;
    int a,b;
        cin>>a>>b;
    n--;
    int flag=1;
    while(n--)
        {
        int aa,bb;
        cin>>aa>>bb;
        if(aa!=a&&bb!=b)
            {
            flag=0;
            break;
        }
            
    }
    if(flag)
        cout<<"YES";
    else 
        cout<<"NO";
    return 0;
}