#!/usr/bin/perl

my $minlen = 4;
my %words;
while (<>) {
  while (/\b(\w+)\b/g) {
    my $w = lc($1);
    next if ($w =~ m/^\d+$/ or length($w) < $minlen);
    $words{$w} += 1;
  }
}

foreach my $k (sort keys %words) {
  print "$k: $words{$k}\n";
}