print "Enter the filename of file having codon data:\n";
$file = <STDIN>;
chomp ($file);
open (IN, $file) or die "Error opening $file: $!\n";
print "\n\n";

while ($seq = <IN>)
{
 print "$seq\n";
 @triplets = unpack ("a3" x (length($seq)/3, $seq);
 print "@triplets\n\n";
}
print "\n\n";