#include <iostream>
using namespace std;

int main()
{

    int  n, points,x[15],y[15],flag = 1;
    cin>>n;
    for(int i = 0; i < n; i++)
    {
        cin>>x[i]>>y[i];
    }

    points = x[0];
    for(int i = 0; i < n; i++)
    {
        if(points != x[i])
        {
            flag = 0;
            break;
        }
    }

    points = y[0];

    if(flag == 0)
    {
        flag =1;

        for(int i = 0; i < n; i++)
        {

            if(points != y[i])
            {

                flag = 0;
                break;
            }
        }

    }

    (flag)? cout<<"YES"<<endl : cout<<"NO"<<endl;


    return 0;
}