def test_simple_test_cases():
assert solve([2, 4, 8, 1, 1]) == 3 + 3
assert solve([2, 4, 9, 1, 1]) == 4 + 4
assert solve([2, 4, 9, 1, 1, 16]) == 4 + 4
assert solve([2, 4, 9, 1, 1, 20]) == 4 + 4
assert solve([1, 4, 1, 4, 1, 4]) == 2 + 2
assert solve([4, 4, 1, 4, 1, 4]) == 2 + 2
assert solve([4, 5, 1, 4, 1, 4]) == 3 + 1 + 3 + 1
def test_large_repeating_sequence():
times = (10**5) // 2
assert solve([2**15, 1] * times) == 15 * times
assert solve([1, 2**15] * times) == 15 * times - 15
def test_large_and_small_numbers_mix():
# second number increased to 2 ** 15, third to 7 * (2 ** 13)
assert solve([2**15, 1, 7 * (2**10), 2**18]) == 15 + 3
def test_impossible_to_get_non_decreasing_sequence():
assert solve([10, 20, 30, 10, 20, 30, 0]) == -1
assert solve([10, 20, 30, 0, 20, 0, 30]) == -1
assert solve([0, 20, 0, 0, 0, 30, 30]) == -1
assert solve([10, 20, 30, 40, 50, 60, 0]) == -1
assert solve([10, 20, 30, 40, 0, 50, 60]) == -1
def test_large_single_number_at_the_start():
# log base 2 of 10**6 is 19.9 aprox; thus, the second number needs to be
# at least 2**20, and the third one needs to be at least 3 * 2**19.
assert solve([10**6, 1, 3]) == 20 + 19
def test_same_number_sequence():
assert solve([5, 5]) == 0
assert solve([10, 10, 10, 10, 10, 10]) == 0
def test_zeros_before_non_zero_numbers():
assert solve([0, 0, 0, 0, 1, 2, 5]) == 0
assert solve([0, 0, 0, 0, 4, 2, 1]) == 3
def test_zeros_only_sequence():
assert solve([0, 0]) == 0
assert solve([0, 0, 0, 0, 0, 0, 0, 0]) == 0
def test_single_element_sequence():
assert solve([0]) == 0
assert solve([1]) == 0
assert solve([10**6]) == 0
def test_challenge_sample_test_cases():
assert solve([3, 2, 1, 5, 4]) == 4
assert solve([1000000, 0]) == -1