print dec2bin(13) . "\n";
	sub dec2bin {
		return (sprintf "%b",shift);
		}

##</code><code>##

	sub to_bin {
		my $num = shift;
		my $ret = '';
		while ($num){
			$ret = (($num % 2) ? 1 : 0);
			$num >>= 1;
			}
		}