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


int main() {
    int n;
    cin >> n;
    bool x,y;
    x=y=1;
    int prevx,prevy;
    for(int i=1;i<=n;++i){
        int a,b;
        cin >> a >> b;
        if(i==1){
            prevx=a;
            prevy=b;
        }
        else
            {
            if(a!=prevx)
                x=0;
            if(b!=prevy)
                y=0;
        }
            
    }
    if(x | y)
        cout << "YES" << endl;
    else
        cout << "NO" << endl;
        
    /* Enter your code here. Read input from STDIN. Print output to STDOUT */   
    return 0;
}