# -*- coding: utf-8 -*-
F = [0, 1/6.0, 1/6.0, 1/6.0, 1/6.0, 1/6.0, 1/6.0]
N = int(input())
MEMO = [0 for i in range(0, N+1)]
for i in range(0, N+1):
    MEMO[i] = 1
    for j in range(1, 7):
        if i - j > 0:
            MEMO[i] += MEMO[i-j] * F[j]
print MEMO[N]