b, g = map(float, input().split(' '))

p= b/(b+g)

def func(n):
    if n == 1 or n==0:
        return 1
    else:
        return n * func(n-1)

def Binomial_Distribution(r, n, p):
    return func(n)/(func(r)*func(n-r))*(p**r)*((1-p)**(n-r))

res = 0.0

for i in range(3, 7):
    res+= Binomial_Distribution(i, 6, p)

print(round(res, 3))