#!/usr/bin/perl
@a = (3,5,2,6);
@b = (7,3,6);
map { $x{$_} = -1 } @a;
map { $x{$_} += 1 } @b;
foreach (sort keys %x){
        $val = $x{$_};
        if(!$val) { print "$_:$_"; }
        elsif($val > 0){ print "-:$_"}
        else{ print "$_:-"};
        print "\n";
}
#@c = ( [2,'-'],[3,3],[5,'-'],[6,6],[7,'-']);