print((function (x, y, l)
	local r = y < 0 and 2 or x ~= 0 and 1 or 0
	return r + math.ceil(math.abs(x)/l) + math.ceil(math.abs(y)/l)
end)(io.stdin:read("*n"), io.stdin:read("*n"), io.stdin:read("*n")))