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

set<int> c, d;

int main() {
    /* Enter your code here. Read input from STDIN. Print output to STDOUT */   
    int x, y, n, i;
    bool flag=true;
    cin>>n;
    for(i=0; i<n; ++i) {
        cin>>x>>y;
        c.insert(x);
        d.insert(y);
    }
    if(c.size()!=1 && d.size()!=1)
        flag=false;
    if(flag)    cout<<"YES\n";
    else    cout<<"NO\n";
    return 0;
}