#! /usr/local/bin/perl
while(<>) {
    foreach (split) {
	$words{lc($_)}++;
    } # end for
} # end while

foreach (sort { return $a cmp $b if ($words{$b} == $words{$a}); return $words{$b} <=> $words{$a}; } keys %words) {
    print "$words{$_}\t$_\n";
}