def fac(num):
    if num==1 or num==0:
        return 1
    else:
        return num * fac(num-1)
s=0
b,g=map(float,input().split())
p=b/(b+g)
for i in range(3,7):
    s+=(fac(6)/(fac(6-i)*fac(i)))*((p)**(i))*((1-p)**(6-i))
print(round(s,3))