#include<stdio.h>
int main()
{
    int n;
    scanf("%d",&n);
    int x[n],y[n];
    int i,count1=0,count2=0;
    for(i=0;i<n;i++)
        scanf("%d%d",&x[i],&y[i]);
    for(i=1;i<n;i++)
    {
        if(x[i-1]==x[i])
            count1++;
        if(y[i-1]==y[i])
            count2++;
    }
    if(count1==n-1 || count2==n-1)
        printf("YES\n");
    else
        printf("NO\n");
    return 0;
}