Hey can someone explain why this doesn't work

Question

Hi I'm pretty new to python and I'm wrighting a program and from some reason the following code doesn't work

strength = 0

strategy = 0

speed = 0

def upgrade ():

  y = input ("what would you like to improve \n1:STRENGTH\n2:SPEED\n3:STRATEGY\n")

  if y == "1":

    strenght = strength + 1

  elif y == "2":

    speed = speed + 1

  elif y == "3":

    strategy = strategy + 1  

time.sleep (1.2)

upgrade ()

It keeps saying that "local variable 'speed' referenced before assignment"

Can someone please explain I have rewriten the code and used 2 different programs to check

Answer 1

I guess one would have to define global variables as such in the body of the function before referring to them inside it:

def upgrade():
global strength, speed, strategy

Answer 2

Also, there seems to be a typo in the first if block, "strengHT" instead of "strength". I guess that's why it only starts complaining when speed is referenced.