def local_maxima(A, ind_left, ind_right):
    # check the edge cases
    if ind_left == 0 and A[ind_left] >= A[ind_left + 1]:
        return ind_left
    elif ind_right == len(A) - 1 and A[ind_right - 1] <= A[ind_right]:
        return ind_right

    ind_mid = (ind_left + ind_right) // 2

    # case 0:
    if A[ind_mid - 1] <= A[ind_mid] >= A[ind_mid + 1]:
        return ind_mid

    # case: 1
    elif A[ind_mid] < A[ind_mid + 1]:
        return local_maxima(A, ind_mid + 1, ind_right)

    # case: 2
    else:
        return local_maxima(A, ind_left, ind_mid - 1)



def main():
    arr = [1, 10, 9, 8, 7]
    assert len(arr) >= 2, "please use an array with length >= 3"

    # Note that the below sorted check is done for validity of question
    # and this logic is not actually part of the solution
    is_ascending = True
    is_descending = True
    for i in range(len(arr) - 1):
        if arr[i] > arr[i + 1]:
            is_ascending = False
        elif arr[i] < arr[i + 1]:
            is_descending = False
    is_sorted = is_ascending or is_descending
    assert is_sorted is False, "please use an unsorted array"

    print(local_maxima(arr, 0, len(arr) - 1))


if __name__ == "__main__":
    main()