import math
A,B = map(int,input().split())
k = math.gcd(A,B)
#print(k)
MAX = 100
ans = 0
for y in range(MAX):
  for x in range(MAX):
    kx = 1 + k*x
    ky = 1 + k*y
    temp = 1/pow(kx+ky,kx+ky)
    #print(kx,ky,temp)
    ans += temp
print(ans)