#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 x,y,xx,yy;
    cin>>x>>y;
    cin>>xx>>yy;
    if (x != xx && y != yy) { cout<<"NO"<<endl; return 0;}
    for(int a0 = 2; a0 < n; a0++){
        int xxx;
        int yyy;
        cin >> xxx >> yyy;
        if (xxx == x && xx == xxx) continue;
        if (yyy == y && yy == yyy) continue;
      cout<<"NO"<<endl; return 0;
    }
    cout<<"YES"<<endl;
    return 0;
}