#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;
    cin >> n;
    int prevx = -1, prevy = -1,fl = 0,ctr = 1;
    if(n == 2){
        int x ,y,a,b ;
        cin >> x >>y >>a >> b;
        if(x == a || y == b){
            cout<<"YES";
            return 0;
        }
        else{
            cout <<"NO";
            return 0;
        }
    }
    for(int a0 = 0; a0 < n; a0++){
        int x;
        int y;
        cin >> x >> y;
        if(prevx == -1 && prevy == -1){
            prevx = x; prevy = y;
        }
        else{
            if(fl == 0){
                if(x == prevx){
                    fl = 1;
                }
                else fl = 2;
            }
            else{
                if(fl == 1){
                    if(x != prevx) ctr =0;
                }
                else {
                    if(y != prevy) ctr = 0;
                }
            }
        }
    }
         if(ctr) cout <<"YES\n";
        else cout <<"NO\n";
   
    return 0;
}