n = int(input())
dp = [[0] * (1 << 6) for _ in range(n)]
p = 1 / 6
for i in range(6):
    dp[0][1 << i] = p
for i in range(n-1):
    for bit in range(1 << 6):
        for j in range(6):
            mask = 1 << j
            dp[i+1][bit | mask] += dp[i][bit] * p
print(dp[-1][(1 << 6) - 1])