N = int(input())
pre = [0] * 7
pre[0] = 1
for i in range(N):
    dp = [0] * 7
    for j in range(1, 7):
        dp[j] += pre[j] * j/6 + pre[j - 1] * (7 - j)/6
    dp, pre = pre, dp
print(pre[-1])