N = int(input())
if N > 100:
    print(1)
else:
    T = [1] + [0]*4
    for n in range(N-1):
        for k in [4, 3, 2, 1]:
            T[k] = T[k]*((k+1)/6) + T[k-1]*((6-k)/6)
        T[0] = T[0]/6
    print(1-sum(T))