#!/usr/bin/perl -w
use strict;

my $string = "1:1,2:1,3:2,500:2,505:1";
my @array_1 = split ",",$string;
my (@array_2, @array_temp, %hash_1);

foreach ( @array_1 ) {
	@array_temp = split ":",$_;
	push @array_2, $array_temp[0];
	$hash_1{$array_temp[0]} = $array_temp[1];
}