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

int main() {

    /* Enter your code here. Read input from STDIN. Print output to STDOUT */    
    int q;
    scanf("%d",&q);
    while(q--){
        int n;
        scanf("%d",&n);
        int a[n],b[n],count=0;
        for(int i=0;i<n;i++){
            scanf("%d %d",&a[i],&b[i]);
            if(i>0){
                if(a[i]==a[i-1] || b[i]==b[i-1] || a[i]==b[i-1] || b[i]==a[i-1])
                    count++;
            }
            
        }
        if(count==n-1)
            printf("YES\n");
        else
            printf("NO\n");
    }
    return 0;
}