#!perl -w

die "usage: flatten <filename>\n" unless (@ARGV == 1);

$file = shift;

open(FILE, "<$file") or die "can't open file '$file': $!\n";

while (<FILE>)
{
    @words = split(/\W+/);
    foreach $word (@words)
    {
        next if (length($word) < 4);
        next if ($word =~ /^[A-Z_]+$/);
        $word =~ tr/A-Z/a-z/;
        $count{$word}++;
    }
}

close(FILE);

foreach $word (sort mysort keys(%count))
{
    printf("%-40s : %6d\n", $word, $count{$word});
}

sub mysort
{
    my($aa,$bb) = ($count{$a},$count{$b});
    if ($aa == $bb)
    {
        return( $a cmp $b );
    }
    else
    {
        return( $bb <=> $aa );
    }
}