#include <stdio.h>
#include <string.h>
#include <math.h>
#include <stdlib.h>
int search(int a[],int key,int len)
    {
        int i;
    for(i=0;i<len;i++)
        {
        if(key==a[i])
            return 1;
    }
        return 0;
}

int main() {
    int q;
    scanf("%d",&q);
    while(q--)
        {
        int n;
        scanf("%d",&n);
        int x[n],y[n];
        int xfind[n],yfind[n];
        int xlen = 0,ylen = 0;
        int i;
        for(i=0;i<n;i++)
            {
            scanf("%d%d",&x[i],&y[i]);
            if(search(xfind,x[i],xlen))
                {
                xfind[xlen] = x[i];
                xlen++;
            }
            if(search(yfind,y[i],ylen))
                {
                yfind[ylen] = y[i];
                ylen++;
            }
        }
        if(n==2||n==1)
            printf("YES\n");
        else
            {
               printf("NO\n");
        }
        
    }
    

    /* Enter your code here. Read input from STDIN. Print output to STDOUT */    
    return 0;
}