#include<bits/stdc++.h>

    using namespace std;

    int main()
    {
        int N;
        bool ver=true, hor=true;
        int x, y;
        int xb, yb;
        cin >> N;
        cin >> x >> y;
        N--;
        xb = x;
        yb = y;

        while(N--){
            cin >> x >> y;
            if(hor and x != xb)
                hor = false;

            if(ver and y != yb)
                ver = false;

            xb = x;
            yb = y;
        }

        if(ver or hor)
            cout << "YES";
        else cout << "NO";

        return 0;
    }