Given some water level $X$, it is easy to compute the
		total volume of water $V(X)$. Basically, one has
		to compute for each object whether it is floating
		or touching the lid. Luckily, $V(X)$ is monotonic
		in $X$. We need to find such $X$ that $V(X) = P$,
		where $P$ is the volume of water in the input data.
		This can be done using binary search. We suggest
		that the complexity of such task is 4 out of 10.

		Another solution, which is much more educating, is
		to observe that the set of possible water levels
		can be split into disjoint set of intervals such
		that within every interval each object is either
		floating or touches the lid. This allows solving
		the task using a linear equation. This is so-called
		"scanning line" principle. Unfortunately we do
		not see any way to force the contestants to use
		this method.