#!/usr/bin/perl -w
                                                                                
use strict;
use warnings;
                                                                                
sub is_incremental {
    my ($word) = @_;
    my @letters = split //, $word;
    my $prev = ord(shift @letters);
    foreach my $letter (@letters) {
        my $next = ord(lc $letter);
        if ($next <= $prev) {
            return 0;
        }
        $prev = $next;
    }
    return 1;
}
                                                                                
my $s = "This is abc and bcf and xyz and ijklmn";
                                                                                
foreach my $word (split /\s+/, $s) {
    if (is_incremental($word)) {
        print "Word [$word] is 'incremental'\n";
    }
}