Trying out my Python 3 skills on HackerRank

I've been using HackerRank to get my Python coding chops up a little better then where they've been before.

Tried a medium challenge on HackerRank called Piling Up

My solution isn't as elegant as others but it works and constantly reduces the size of the cube size list that need to be rearranged from horizontal to vertical where the block size needs to be equal or smaller than the block below it.

for tests in range(int(input())):

    cube_length = int(input())

    list_of_cubes = list(map(int, input().split()))

    last_value_placed_on_stack = 0

    all_items_on_placed_on_stack = False

    cannot_stack_anymore = False

    a = 0

    z = int(len(list_of_cubes)) - 1

    while a < int(len(list_of_cubes)):

        if cannot_stack_anymore:

            break

        if int(len(list_of_cubes)) == 1:

            if int(list_of_cubes[a]) <= last_value_placed_on_stack:

                all_items_on_placed_on_stack = True

                break

            else:

                break

        while z > 0:

            if list_of_cubes[a] >= int(list_of_cubes[z]):

                if list_of_cubes[a] <= last_value_placed_on_stack or last_value_placed_on_stack == 0:

                    last_value_placed_on_stack = list_of_cubes[a]

                    list_of_cubes.pop(a)

                    z = z - 1

                    break

                else:

                    cannot_stack_anymore = True

                    break

            if list_of_cubes[z] >= int(list_of_cubes[a]):

                if list_of_cubes[z] <= last_value_placed_on_stack or last_value_placed_on_stack == 0:

                    last_value_placed_on_stack = list_of_cubes[z]

                    list_of_cubes.pop(z)

                    z = z - 1   

                    break

                else:

                    cannot_stack_anymore = True

                    break

    if all_items_on_placed_on_stack:

        print("Yes")

    else:

        print("No")