from math import gcd
A,B=map(int,input().split())

if A==B==0:
    print(0.25)
else:
    g=gcd(A,B)
    X=0

    if g<=20:
        T=10
    else:
        T=2

    if (A//g)%2==(B//g)%2==1:
        for k in range(T):
            h=2*k*g+2
            X+=(2*k+1)/(h**h)
    else:
        for k in range(T):
            h=k*g+2
            X+=(k+1)/(h**h)
    print(X)