#!/usr/bin/perl -w
# if-elsif-else

$word = 'MNIDDKL';

# if-elsif-else conditionals
if($word eq 'QSTVSGE') {

    print "QSTVSGE\n";

} elsif($word eq 'MRQQDMISHDEL') {

    print "MRQQDMISHDEL\n";

} elsif ( $word eq 'MNIDDKL' ) {

    print "MNIDDKL-the magic word!\n";

} else {

    print "Is \"$word\" a peptide? This program is not sure.\n";

}