#include <stdio.h>

int main()
{
    int a,n,x,y,x1,y1,count1=1,count2=1; 
    scanf("%d",&n);
    
    scanf("%d%d",&x1,&y1);
    
    for(a = 1; a < n; a++)
    {
        scanf("%d %d",&x,&y);
        
        if(x==x1)
            count1++;
        else if (y==y1)
            count2++;
    }
    
    if(count1==n || count2==n)
        printf("YES");
    else
        printf("NO");
    
    return 0;
}