Where am I making a mistake?(Python random.randint)

In a race, I try to find the percentage probabilities of the competitors to move forward, backward and stay still.but I'm making a mistake.(I have to prevent the competitors from going off the track.)

def move(a): x = random.randint(1, 10)

if x == 1:
    if a > 2:
        return a - 2
    else:
        return 0

if x == 1:
  return a + 2 
else:
  return a 


if 1<=x<=3:
  if a > 1:
    return a - 1
  else:
    return 0

if 1<=x<=3:
  return a + 1
else :
  return a



if 3<=x<=5:
  return a + 1
else:
  return a