#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 */   
    
    unsigned count;
    cin >> count;
    
    unsigned prevx, prevy;
    bool dx = false, dy = false;
    
    for (unsigned i = 0; i < count; ++i){
        
        unsigned x, y;
        cin >> x >> y;
        
        if (i > 0){
            if (x != prevx){
                dx = true;
            }
            if (y != prevy){
                dy = true;
            }
        }
        
        if (dx && dy){
            cout << "NO" << endl;
            return 0;
        }
        
        prevx = x;
        prevy = y;
        
        
    }
    
    cout << "YES" << endl;
    
    return 0;
}