Does there exist a covering of a square?

Question

Consider a square of length $ S \in \mathbb{N} $ and a given set $ M $ of $ t \in \mathbb{N} $ smaller squares of lengths $ s_1,\ldots,s_t \in \mathbb{N} $. Are there any conditions, so that I can see, whether the square $ S $ can be covered by the set $ M $ of smaller squares? (A rotation of the items is not allowed, they have to be axis-parallel. The covering has to be non-overlapping, i.e. two items of $ M $ are not allowed to share a common interior point of themselves.)