sub zeller
{
	my ($y, $m, $d) = @_;
	return ($y + $y / 4 - $y / 100 + $y / 400 + (13 * $m + 8) / 5 + $d) % 7;
}

$s = 0;
for ($y = 1901; $y <= 2000; ++$y) {
	for ($m = 1; $m <= 12; ++$m) {
		if (zeller($y, $m, 1) == 1) {
			++$s;
		}
	}
}
print $s;