#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;
    int px;
    int py;
    int kx=0;
    int ky=0;
    cin >> n;
    for(int a0 = 0; a0 < n; a0++){
        int x;
        int y;
        cin >> x >> y;
        if(!a0){
            px = x;
            py = y;
            continue;
        }
        if(x==px){
            kx++;
        } else if(y==py){
            ky++;
        } else{
            cout<<"NO\n";
            return 0;
        }
    }
    if(!ky || !kx)
        cout<<"YES\n";
    else
        cout<<"NO\n";
    return 0;
}