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


int main() {
    int a,b,x,y,n,fa=0,fb=0;
    cin>>n;
    for(int i=0;i<n;i++)
        {
        cin>>a>>b;
        if(i==0){
            x=a;
            y=b;
        }
        if(x!=a) fa=1;
        if(y!=b) fb=1;
    }
    if(fa==0 || fb==0) cout<<"YES"<<endl;
    else cout<<"NO"<<endl;
    return 0;
}