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

int main(){
    ll n;
    cin>>n;
    int x[n],y[n];
    for(int i=0;i<n;i++){
        cin>>x[i]>>y[i]; 
    }
    int k=0;
    int h=0;
    for(int i=0;i<n-1;i++){
        if(x[i]!=x[i+1]){k=1;}
        if(y[i]!=y[i+1]){h=1;}
    }
    if(k==0 || h==0){cout<<"YES"<<endl;}
    else{cout<<"NO"<<endl;}
}