#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 x[n],y[n];
    for(int i=0;i<n;i++)
        cin>>x[i]>>y[i];
    int flag=1;
    for(int i=1;i<n;i++){
        if(x[i]!=x[i-1]){flag=0;break;}
    }
    for(int i=1;i<n && flag!=1;i++)
        {
        if(y[i]!=y[i-1]){flag=0;break;}
    }
    if(flag==1)cout<<"YES\n";
    else cout<<"NO\n";
    return 0;
}