#include<bits/stdc++.h>
using namespace std;
map<int , int> xx,yy;
int main()
    {
    int n,x,y;
    cin>>n;
    for(int i=0;i<n;i++){
        cin>> x >> y;
        xx[x]++;yy[y]++;
    }
    if(xx[x]==n || yy[y]==n)cout << "YES\n";
    else cout << "NO\n";
}