#!/usr/bin/perl -w

use strict;

my %histogram;
my @wordstofind = qw(
a am an and are as at be been but by can co de do due each 
); #Many more words snipped 

while (<STDIN>) {
        my @currentline = split;
        $histogram{$_}++ for @currentline;
}

foreach my $i (@wordstofind) {
        while ( my ($key, $value) = each (%histogram) ) {
                if ($key =~ /$i/) {
                        print "Found $key, $value times\n";
                }
        }

}