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

if A==B==0:
    print(0.25)
elif A==0 or B==0:
    C=max(abs(A),abs(B))
    if C>=9:
        print(0.25)
    else:
        print(1/0)
        print([0.2912859971, 0.2539277432, 0.2503200596, 0.2500214336, \
0.2500012143, 0.2500000596, 0.2500000026, 0.2500000001][C-1])
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)