#include <iostream>
using namespace std;

int n, x[100], y[100], k, p;

int main()
{
    cin >> n;
    cin >> x[1] >> y[1];
    k = 1;
    p = 1;
    for(int i = 2; i <= n; i++)
    {
            cin >> x[i] >> y[i];
            if (x[i] != x[i - 1]) k = 0;
            if (y[i] != y[i - 1]) p = 0;
    }
    
    if (k + p > 0) cout << "YES";
    else cout << "NO";
    
    
    //system("pause");
    return 0;
}