#include <cmath>
#include <cstdio>
#include <vector>
#include <iostream>
#include <algorithm>
using namespace std;


int main() {
    /* Enter your code here. Read input from STDIN. Print output to STDOUT */   
    int n,l[20],r[20],i=0,k=0;
    scanf("%d",&n);
    for(i=0;i<n;i++)
        {
        scanf("%d%d",&l[i],&r[i]);
    }
    for(i=0;i<n-1;i++)
        {
        if((l[i]==l[i+1]) ||(r[i]==r[i+1]))
            {}
        else
            {k++;}
    }
    if(k==0)
        {
        printf("YES");
    }
    else
        {
        printf("NO");
    }
    return 0;
}