N = int(input())
dp = [0] * 7
dp[0] = 1
ans = 0
for i in range(N):
    dp2 = [0] * 7
    for j in range(1, 7):
        dp2[j] = dp[j - 1] * (7 - j) / 6 + dp[j] * j / 6
    dp = dp2
print(dp[6])