Python: NameError: name 'u' is not defined

i am completing a simple class asignment with functions. We have to find for which month m the functioncontract_v will be more advantageous than the contract_u. This is the code I wrote:

def contract_u(m):
  u=1000
  for i in range (m):
    u=u+80
  return u

def contract_v(m):
  v=1000
  for i in range (m):
    v=v*1.05
  return v

m=1
if u>v:
  m=m+1
else:
  print(m)

However, the computer says this:

---------------------------------------------------------------------------
NameError                                 Traceback (most recent call last)
<ipython-input-20-8909d368129a> in <module>()
     12 
     13 m=1
---> 14 if u>v:
     15   m=m+1
     16 else:

NameError: name 'u' is not defined

I do not understand what I have to modify and why the code is not functionning properly. If you do know what has been done wrong, please point that out. Thank you in advance.

your variables are defined locally in your functions, so they do not exist outside of them, so you should add these lines before your if statement :

u=contract_u(m)
v=contract_v(m)