#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 const_x=0 ,const_y=0;
    cin >> n;
    for(int a0 = 0; a0 < n; a0++){
        int x;
        int y;
        cin >> x >> y;
        if(a0==0){
           const_x =x;
            const_y = y;
        }
        
        if(const_x != x){
            const_x = -11;
        }
        if(const_y != y){
            const_y = -11;
        } 
    }
    if(const_x == -11 && const_y==-11){
            cout<<"NO"<<endl;
        }else{
            cout<<"YES"<<endl;
        }
    return 0;
}