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

ll gcd(ll a,ll b){
    if(a==0) return b;
    return gcd(b%a,a);
}

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