#include <iostream>
#include <algorithm>
#include<set>
using namespace std;

int main() {
    int n;
    cin >> n;
    set<int> A,B;

    for(int i = 0; i < n; i++){
        int a,b;
        cin>> a >> b;
        A.insert(a);
        B.insert(b);
    }
    if(A.size() == 1 or B.size() == 1) cout << "YES" << endl;
    else cout << "NO" << endl;
    return 0;
}