import math;A,B=map(int,input().split())
if A|B==0:print(1/4);exit()
g=math.gcd(A,B);X=0;T=8*(g<=9)+2;F=A//g%2*B//g%2+1;k=0
while k<T:h=F*k*g+2;X+=(F*k+1)/h**h;k+=1;
print(X)