import numpy as np

N = int(input())
dp = np.zeros(7, dtype=float)
dp[0] = 1.0
for _ in range(N):
    new_dp = dp * np.arange(7) / 6
    new_dp[1:] += dp[:-1] * np.arange(6, 0, -1) / 6
    dp = new_dp
print(dp[6])