/* THE GUY WHO WAS
                                                                           Strong,
                                                                        Emotionless,
                                                                           Asshole,
                                                                            Bitch,
                                                                            Jerk,
                                                                         Narcissist,
                                                                          Selfish,
                                                                           Smart
                                                                            And
                                                              Knew How To Kill, Conquer And Win
                                                                         IS BACK.....*/




#include<bits/stdc++.h>
using namespace std;
typedef long long LL ;
#define get(a) for( int i = 0; i < n; i++) cin >> a[i] ;

int main(){
    int n;
    cin >> n;
    int a[n], b[n], flag1 = 0, flag2 = 0;

    for(int i = 0 ; i < n; i++) cin >> a[i] >> b[i];

    for(int i = 0; i < n - 1; i ++){
        if(a[i]!= a[i+1]){
            flag1 = 1;
            break;
        }
    }
    for(int i = 0; i < n - 1; i ++){
        if(b[i]!= b[i+1]){
            flag2 = 1;
            break;
        }
    }
    if(!flag1 || !flag2)cout << "YES\n";
    else cout << "NO\n" ;
    return 0;
}