t = int(input())
# for i in range(t):

dp = [0] * (10 ** 6 + 1)
rate = [0] * 6
dp[0] = 1

answer = [1.,
1.0833333333333333,
1.2569444444444444,
1.5353009259259260,
1.6915991512345676,
2.0513639724794235]

for i in range(1, len(dp)):
    tmp = 0
    for j, k in zip(reversed(dp[max(0, i - 6):i]), rate):
        tmp += j * k
    if i < 6:
        rate[i-1] = answer[i] - tmp - 1
        tmp = 0
        for j, k in zip(reversed(dp[max(0, i - 6):i]), rate):
            tmp += j * k
        dp[i] = 1 + tmp
    elif i == 6:
        rate[i-1] = 1 - sum(rate)
        tmp = 0
        for j, k in zip(reversed(dp[max(0, i - 6):i]), rate):
            tmp += j * k
        dp[i] = 1 + tmp
    else:
        dp[i] = 1 + tmp
#     print(tmp, rate, list(reversed(dp[max(0, i - 6):i])))
print(dp[t-1])