#include <bits/stdc++.h>

using namespace std;

int ans;
int x[100],y[100];
int n;
int main()
{  int q;
 cin>>q;
while(q--)
{
    cin>>n;
    for (int i=1;i<=n;i++)
        scanf("%d%d",&x[i],&y[i]);
         int o=0;
       
        for (int i1=1;i1<=n;i1++)
        for (int i2=1;i2<=n;i2++)
        for (int j1=1;j1<=n;j1++)
        for (int j2=1;j2<=n;j2++)
        { 
            ans=0;
        for (int p=1;p<=n;p++)
            if (x[i1]==x[p] && y[p]>=min(y[j1],y[j2]) && y[p]<=max(y[j1],y[j2]) ) ans++; else
            if (x[i2]==x[p] && y[p]>=min(y[j1],y[j2]) && y[p]<=max(y[j1],y[j2]) ) ans++; else
            if (y[j1]==y[p] && x[p]>=min(x[i1],x[i2]) && x[p]<=max(x[i1],x[i2]) ) ans++; else
            if (y[j2]==y[p] && x[p]>=min(x[i1],x[i2]) && x[p]<=max(x[i1],x[i2]) ) ans++; 
        if (ans==n && o==0)
        o=1;
        }
         if (o==0) printf("NO\n"); else printf("YES\n");
        
}
return 0;
}