text: # Tutorials > 10 Days of Statistics > Day 4: Binomial Distribution I
  # Problems based on basic statistical distributions.
  #
  
  from math import factorial
  
  # b(x,n,p) = C(n,p) * p^x * (1-p)^(n-x)
  
  # x: number of successes
  # n: total number of trials
  # p: probability of success of 1 trial
  
  def b(n, x, p):
      return factorial(n) // factorial(n - x) // factorial(x) * (p ** x) * (1 - p) ** (n - x)
  
  
  boys, girls = map(float, input().split())
  
  p = boys / (boys + girls)
  
  r = b(6, 3, p) + b(6, 4, p) + b(6, 5, p) + b(6, 6, p)
  
  print("%.3f" % r)
  