Problem with elif statement

[Haddal99]

I'm completely new to Python (and programming in general) and I can't wrap my head around why this piece of code doesn't work:

posx = 0
posy = 0
doForever = True

while doForever == True:
  if input() == "forward":
    posy += 1
    print(posy)
  elif input() == "backward":
    posy -= 1
    print(posy)

It's supposed to check if the player inputs "forward" or "backward" and update the ypos accordingly. But what actually happens is that if you input "backward", it only works exactly half of the time. The "forward" one works correctly, but the "backward" only returns the updated variable every other time it's used. Help would be much appreciated; thanks in advance.