text: score=input("Enter the score between 0.0 and 1.0")
  
  try:
      score=float(score)
  except:
      print("Please enter numbers")
      quit()    
  
  if (score < 0) or (score > 1):
      print("Invalid input. Score out of range")
  elif score >=0.9:
      print("A")
  elif score >=0.8:
      print("B")
  elif score >=0.7:
      print("C")
  elif score >=0.6:
      print("D")
  else:
      print("F")
  