use strict;
use warnings;

use CGI;
my $q = CGI::new;
# or however you get your $q ...

# input names look like "id1~id2~id3"
# or pick a delimiter you like instead of ~
for my $param ($q->param) {
    # print "$param<br/>\n";
    next unless $param =~ /.*(?:~.+){2}/;
    my ($id1,$id2,$id3) = split(/~/,$param);
    # print "$id1 - $id2 - $id3<br/>\n";
    # ...
}