#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,x,y,z,w;
    cin >> n;
    bool vert=0,hor=0;
    cin >> x >>y >> z >> w;
    if(x==z) vert = 1;
    if(y==w) hor = 1;
    n-=2;
    if(!vert && !hor ) {cout << "NO" << endl;return 0;}
    while(n--){
        cin >> z >> w;
        if(vert){
            if(x!=z) 
                {cout << "NO" << endl;return 0;}
        }
        else{
            if(y!=w){cout << "NO" << endl;return 0;}
        }
       
    }
    cout << "YES" << endl;
    return 0;
}