#include <map>
#include <set>
#include <list>
#include <cmath>
#include <ctime>
#include <deque>
#include <queue>
#include <stack>
#include <string>
#include <bitset>
#include <cstdio>
#include <limits>
#include <vector>
#include <climits>
#include <cstring>
#include <cstdlib>
#include <fstream>
#include <numeric>
#include <sstream>
#include <iostream>
#include <algorithm>
#include <unordered_map>

using namespace std;


int main(){
    int n,x,y,X,Y;
    cin >> n;
    cin >> x >> y;
        X=x;Y=y;
    cin >> x >> y;
    if(x==X)
    {
        for(int a0 = 0; a0 < n-2; a0++){

            cin >> x >> y;
            if(x!=X)
            {
                cout<<"NO";
                return 0;
            }
        }
    }else if(y==Y)
    {
            for(int a0 = 0; a0 < n-2; a0++)
            {
                cin >> x >> y;
                if(y!=Y);
                {
                    cout<<"NO";
                    return 0;
                }

            }
    }
    else{
            cout<<"NO";
            return 0;    
    }
         cout<<"YES";
        return 0;
}