from scipy.special import zeta

def main():
    X,K=map(int, input().split())
    if X==1:
        print(1-1/2**(K+1))
    if X==2:
        if K==1:
            print(1/2)
        elif K==2:
            print(zeta(2)-1)
        else:
            print((K-1)*zeta(K)  - (K-2)*zeta(K-1))

main()