from math import gcd
A, B = map(int, input().split())
A = abs(A)
B = abs(B)
ans = 0
if A==B==0:
  ans = 1/4
elif A==B:
  for i in range(1,21):
    for j in range(1,21):
      if (i+j-2)%(2*A)==0:
        ans += 1/pow(i+j,i+j)
elif A==0:
  for i in range(1,21,B):
    ans += 1/pow(i+1,i+1)
elif B==0:
  for i in range(1,21,A):
    ans += 1/pow(i+1,i+1)
else:
  g1 = gcd(A+B,A-B)
  g2 = gcd(A,B)
  for i in range(1,21, g2):
    for j in range(1,21, g2):
      if (i+j-2)%g1==0:
        ans += 1/pow(i+j,i+j)
print(ans)