Answer:
def theRoundTrip(movement):
  x=0
  y=0
  for i in movement:
    if i not in ["U","L","D","R"]:
      print("bad input")
      return
    if i=="U":
      y+=1
    if i=="L":
      x-=1
    if i=="D":
      y-=1
    if i=="R":
      x+=1
  return x==0 and y==0