#!/usr/bin/python

# P2PU - Python Programming 101 - Chapter 8 - Functions
# Python for Informatics - Chapter 4 - Functions
# Exercise 4.7

def computegrade(score):
    if num < 0.0 or num > 1.0 : grade = 'Bad score!'
    elif num >= 0.9 : garde = 'A'
    elif num >= 0.8 : grade = 'B'
    elif num >= 0.7 : grade = 'C'
    elif num >= 0.6 : grade = 'D'
    else : grade = 'F'
    return grade

try:
    num = float(raw_input('Enter a number between 0.0 and 1.0: '))
    print 'Grade:', computegrade(num)
except:
  print 'Bad score!'