import os
import sys

import numpy as np

if os.getenv("LOCAL"):
    sys.stdin = open("_in.txt", "r")

sys.setrecursionlimit(10 ** 9)
INF = float("inf")
IINF = 10 ** 18
MOD = 10 ** 9 + 7
# MOD = 998244353


K = int(sys.stdin.buffer.readline())

# X[i] = sum(X[i+1:i+7]) + 1
# 反復法で解く
ans = np.ones(K + 10)
ans[K] = 0
for _ in range(10000):
    cs = ans.cumsum()
    ans[:K] = (cs[6:] - cs[:-6])[:K] / 6 + 1
    ans[K + 1:] = ans[0]
print(ans[0])