#! perl -slw
use strict;

open W, '<', 'words.txt' or die $!;
my @words = <W>;
close W;
chomp @words;

chomp( my $bad = lc shift() );

for my $good ( @words ) {
    next if length $good != length $bad;
    my $mask = $good ^ $bad;
    my $match = $mask =~ tr[\0][];
    next unless $match;
    printf "$bad has a %.2f%% chance of being: $good \n", 
        $match / length( $good ) * 100;
}