#include <stdio.h>
#include <stdlib.h>


int main(){
    int n; 
    scanf(" %d", &n);
    int first_x, first_y;
    scanf(" %d %d", &first_x, &first_y);
    int x, y;
    for(int a0 = 1; a0 < n; a0++){
        scanf(" %d %d",&x,&y);
        if ((first_x - x) && (first_y - y)) {
          printf("NO\n");
          return 0;
        }
    }
    printf("YES\n");
    return 0;
}