def add(*matrices):
    m_sizes = [len(matrix) for matrix in matrices]
    v_sizes = [len(vectors) for matrix in matrices for vectors in matrix]
    same_values = lambda l: all(e == l[0] for e in l[1:])
    if not same_values(m_sizes) or not same_values(v_sizes):
        raise ValueError("Given matrices are not the same size.")
    return [[sum(elt) for elt in zip(*vectors)] for vectors in zip(*matrices)]