#!/usr/bin/perl

use strict;

use Data::Dumper qw(Dumper);

my $q = <STDIN>;
chomp $q;

for my $asd ( 1 .. $q ) {
    my $n = <STDIN>;
    chomp $n;

    my $minx = 10000;
    my $miny = 10000;
    my $maxx = 0;
    my $maxy = 0;

    my @pts;

    for ( 1 .. $n ) {
        my $ln = <STDIN>;
        chomp $ln;

        my ( $x, $y ) = split( ' ', $ln );

        $minx = $x if $x < $minx;
        $miny = $y if $y < $miny;

        $maxx = $x if $x > $maxx;
        $maxy = $y if $y > $maxy;

        push @pts, "$x|$y";
    }

    my $last = 0;

    for my $p (@pts) {
        my ( $x, $y ) = split( /\|/, $p );

        if ( $x == $minx or $x == $maxx ) {
            ## cmp y
            if ( $y < $miny or $y > $maxy ) {
                print "NO\n";
                $last = 1;
                last;
            }
        }
        elsif ( $y == $miny or $y == $maxy ) {
            if ( $x < $minx or $x > $maxx ) {
                print "NO\n";
                $last = 1;
                last;
            }

        }
        else {
            print "NO\n";
            $last = 1;
            last;
        }

    }

    next if $last;
    
    print "YES\n";

}