#!/usr/bin/env perl

use strict;
use warnings;

my %count;
my @words = qw(Bob Tom Dave John Jeremy Max Tom Harold Tom Bob Pete Pete Frank Tom);

my $wordcnt='Bob|Tom|Dave|Tom|Bob|Dave';

foreach my $word (@words){
    if($word=~/($wordcnt)/io){
        $count{$1}++;
    }
}

print "$_ => $count{$_}\n" for sort keys %count;