#!/usr/bin/perl
$limit = $ARGV[0];
$|=1;
while(read(STDIN,$buffer,1)) {
	if ($buffer =~ /a/i || $buffer =~ /b/i) {
		print ".";
		$count++;
		if ($count == $limit) {
			print "\n";
			$count=0;
		}	
	}
}