def matrix_multiply_naive(A: list[list[int]], B: list[list[int]]) -> list[list[int]]:
    n = len(A)
    C = [[0] * n for _ in range(n)]
    for i in range(n):
        for j in range(n):
            for k in range(n):
                C[i][j] += A[i][k] * B[k][j]
    return C

if __name__ == "__main__":
    A = [[1, 2], [3, 4]]
    B = [[5, 6], [7, 8]]
    print(matrix_multiply_naive(A, B))
    # [[19, 22], [43, 50]]