#include <math.h>
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <assert.h>
#include <limits.h>
#include <stdbool.h>

int main(){
    int n,flag,a,b,i;
    int x1[10],y1[10];
    scanf("%d",&n);
    for(int a0 = 0; a0 < n; a0++){
        int x; 
        int y; 
        scanf("%d %d",&x,&y);
        x1[a0] =x;
        y1[a0] =y;
    }
    x1[0] = a;
    y1[0] =b;
    flag=0;
    for(i=1;i<n;i++){
        
        if(x1[i] != a)
            break;
        else if(i ==n-1)
            flag=1;
        
    }
    for(i=1;i<n;i++){
        
        if(y1[i] != b)
            break;
        else if(i ==n-1)
            flag=1;
        
    }
    if(flag==0)printf("NO");
    else printf("YES");
    return 0;
}