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

int main() {
    int queries;
    scanf("%d",&queries);
    for(;queries;queries--)
        {
        int i,pts,flag = 0,twoocc = 0,oneocc = 0;
        scanf("%d",&pts);
        int points[10][2];
        int unix[2] = {0};
        int uniy[2] = {0};
        for(i=0;i<pts;i++) scanf("%d %d",&points[i][0],&points[i][1]);
        for(i=0;i<pts;i++)
            {
            if(points[i][0] == unix[0] && oneocc) continue;
            if(unix[1] == points[i][0] && twoocc) continue;
            if(oneocc = 0)
                {
                unix[0] = points[i][0];oneocc = 1;
            }
            if(points[i][0] != unix[0])
                {
                if(twoocc == 0)
                    {
                    unix[1] = points[i][0];twoocc = 1;
                }
                if(twoocc == 1 && points[i][0] != unix[1]) flag =1;
            }
        }twoocc = 0;oneocc = 0;
        for(i=0;i<pts;i++)
            {
            if(points[i][1] == uniy[0] && oneocc) continue;
            if(uniy[1] == points[i][1] && twoocc) continue;
            if(oneocc = 0)
                {
                uniy[0] = points[i][1];oneocc = 1;
            }
            if(points[i][1] != uniy[0])
                {
                if(twoocc == 0)
                    {
                    uniy[1] = points[i][1];twoocc = 1;
                }
                if(twoocc == 1 && points[i][1] != uniy[1]) flag =1;
            }
        }
      if(flag) printf("NO\n");
      else printf("YES\n");
    }
    return 0;
}