#!/usr/bin/perl
use strict;
use warnings;
# use integer;

my %iupac_dgn;
my @iupac_code=('M','R','W','S','Y','K','V','H','D','B','N');
my @iupac_den=('2','2','2','2','2','2','3','3','3','3','4');
@iupac_dgn{@iupac_code}=@iupac_den;

my $string = 'GGNMDNNSNNNNDBNVWVSMNNHYNBNG';
my @residues = split( //, $string );
my $degeneracy = 1;

foreach my $residues(  @residues  ) {
    if(  grep( m/^$residues$/, keys %iupac_dgn )  ) {
        my $factor = $iupac_dgn{$residues};
        $degeneracy = ($factor * $degeneracy);
    }
}

printf "%28s, %30d", $string, $degeneracy;
__END__
GGNMDNNSNNNNDBNVWVSMNNHYNBNG,                  2348273369088