my @arr4 = sort { $a->[0] cmp $b->[0] } @un_sorted;

print "Mutli-Dimensional Array\n";

for my $i ( 0 .. $#arr4) {
    for my $j (0 .. $#{$arr4[$i]}) { 
       print "$arr4[$i][$j]\t";
    }
    print "\n";
}