#! perl -slw
use strict;

sub dedup {
	my $ref = shift;
	my ($i, %h) = 0;
	while( $i < @$ref ) {
		my $v = $ref->[$i];
		unless( exists $h{$v} ) {
			$h{$v}=undef;
			$i++;
			next;
		}
		splice @{$ref}, $i, 1;
	}
}
my @a = (7, 20..30, 1..1000, 200..300, 7);

print scalar @a;
dedup \@a;
print scalar @a;
#print "@a";