#include <stdio.h>
#include <string.h>
#include <math.h>
#include <stdlib.h>
int mod(int x)
    {
    if(x>=0)return x;
    x*=(-1);
    return x;
}
int main() {

    /* Enter your code here. Read input from STDIN. Print output to STDOUT */    
    int t;
    scanf("%d",&t);
    while(t--)
        {
        int n;scanf("%d",&n);
        int x[n],y[n],i,j,k,l,g,f=0;
        for(i=0;i<n;i++)
            scanf("%d %d",&x[i],&y[i]);
        int ax,ay,bx,by;
        for(i=0;i<n;i++)
            {
            for(j=0;j<n;j++)
                {
                for(k=0;k<n;k++)
                    {
                    for(l=0;l<n;l++)
                        {
                        ax=x[i];bx=x[j];
                        ay=y[k];by=y[l];
                        
                        if(mod(ax-bx)==mod(ay-by)|| 1)
                            {
                            f=0;
                            for(g=0;g<n;g++)
                                {
                                if(x[g]==ax || x[g]==bx)
                                    {
                                    if(ay>by )
                                        {
                                        int t=ay;
                                        ay=by;
                                        by=t;
                                    }
                                    if(y[g]<=by && y[g]>=ay)
                                        {}
                                    else
                                        f=1;
                                }
                                else if(y[g]==ay || y[g]==by)
                                    {
                                    if(ax>bx )
                                        {
                                        int t=ax;
                                        ax=bx;
                                        bx=t;
                                    }
                                    if(x[g]<=bx && x[g]>=ax)
                                        {}
                                    else
                                        f=1;
                                }
                                else
                                    f=1;
                            }
                            if(f==0)
                                {i=j=k=l=n;}
                        }
                    }
                }
            }
        }
        if(f==0)
            printf("YES\n");
        else
            printf("NO\n");
    }
    return 0;
}