# Learn Recursion by Solving the Tower of Hanoi Puzzle - Step 38

### Tell us what’s happening:

The question is to verify if `n` (`NUMBER_OF_DISKS`, as defined on step 9) is odd, and the only way I know to do it is using `n % 2`, where when 1 `n` is odd, and when its 0 `n` is even.

I’ve tried so many patterns using that logic, but nothing happened.

``````NUMBER_OF_DISKS = 4
number_of_moves = 2**NUMBER_OF_DISKS - 1
rods = {
'A': list(range(NUMBER_OF_DISKS, 0, -1)),
'B': [],
'C': []
}

def make_allowed_move(rod1, rod2):
forward = False
if not rods[rod2]:
forward = True
elif rods[rod1] and rods[rod1][-1] < rods[rod2][-1]:
forward = True

if forward:
print(f'Moving disk {rods[rod1][-1]} from {rod1} to {rod2}')
rods[rod2].append(rods[rod1].pop())
else:
print(f'Moving disk {rods[rod2][-1]} from {rod2} to {rod1}')
rods[rod1].append(rods[rod2].pop())

# display our progress
print(rods, '\n')

def move(n, source, auxiliary, target):
# display starting configuration
print(rods, '\n')
for i in range(number_of_moves):
remainder = (i + 1) % 3

/* User Editable Region */

if remainder == 1:
# I also tried:
# - NUMBER_OF_DISKS % 2 != 0;
# - not NUMBER_OF_DISKS % 2 == 0;
# - and all that using 'i'
if NUMBER_OF_DISKS % 2 == 1:
print(f'Move {i + 1} allowed between {source} and {target}')
make_allowed_move(source, target)

/* User Editable Region */

elif remainder == 2:
print(f'Move {i + 1} allowed between {source} and {auxiliary}')
make_allowed_move(source, auxiliary)
elif remainder == 0:
print(f'Move {i + 1} allowed between {auxiliary} and {target}')
make_allowed_move(auxiliary, target)

# initiate call from source A to target C with auxiliary B
move(NUMBER_OF_DISKS, 'A', 'B', 'C')
``````

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### Challenge Information:

Learn Recursion by Solving the Tower of Hanoi Puzzle - Step 38

I’m seeing in the instructions

Add a nested `if` to execute when `n` is odd

I’m not sure where `NUMBER_OF_DISKS` comes in, but I don’t think that’s what this step wants. Your code works when I use `n`.

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Oh, I didn’t see that `n` was really a variable… I just forgot that completely. I will try it right now, thank you man!

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