
while True:
  try:
    num_cows, num_cars, num_show = list(map(int, input().split()))
    total = num_cars + num_cows 
  
    if num_show >= num_cows:
      p = 1
    else:
      p = (num_cars / total) * ( (num_cars - 1) / (total - 1 - num_show ) )
      p += (num_cows / total) * (num_cars / (total - 1 - num_show))
    
    print("{0:.5f}".format(p))
  except EOFError:
    break

2da49c0ef434087c82c8b639fd21d6e10698073a
<mask token>

while True:
    try:
        num_cows, num_cars, num_show = list(map(int, input().split()))
        total = num_cars + num_cows
        if num_show >= num_cows:
            p = 1
        else:
            p = num_cars / total * ((num_cars - 1) / (total - 1 - num_show))
            p += num_cows / total * (num_cars / (total - 1 - num_show))
        print('{0:.5f}'.format(p))
    except EOFError:
        break


while True:
  try:
    num_cows, num_cars, num_show = list(map(int, input().split()))
    total = num_cars + num_cows 
  
    if num_show >= num_cows:
      p = 1
    else:
      p = (num_cars / total) * ( (num_cars - 1) / (total - 1 - num_show ) )
      p += (num_cows / total) * (num_cars / (total - 1 - num_show))
    
    print("{0:.5f}".format(p))
  except EOFError:
    break
