#!/usr/bin/env perl

use strict;
use warnings;
use feature 'say';
use utf8;
use open qw(:std :utf8);

my $WIDTH_DEFAULT = 80;
my $WIDTH         = $ARGV[0] || $WIDTH_DEFAULT;

sub main {
	my $buf = '';
	while (my $line = <STDIN>) {
		if ($line =~ /^\s+$/) {
			say $buf;
			say '' if ($buf);
			$buf = '';
			next;
		}
		if ($buf) {
			$line = $buf . $line;
		}
		my ($head, $tail) = handle_str($line);
		say $head;
		$buf = handle_buf($tail);
	}
	say $buf if $buf;	
}

sub handle_buf {
	my $buf = shift;
	my $len = length($buf);
	if ($len == $WIDTH) {
		say $buf;
		return '';
	}
	if ($len < $WIDTH) {
		return $buf;
	}
	## $len > $WIDTH
	my ($head, $tail) = handle_str($buf);
	say $head;
	handle_buf($tail);
}

sub handle_str {
	my $str = shift;
	if ($str =~ m/^(.{0,$WIDTH})\s(.*)$/) {
		return ($1, $2);
	}
	## no spaces here: 0..$WIDTH
	if ($str =~ m/^(\S*)\s(.*)$/) {
		return ($1, $2);
	}
	## no whitespace at all
	if ($str =~ m/^(\S+)$/) {
		return ($1, '');
	}
	die "ooops!";
}

main();