n = int(input())
dp = [0]*6
dp[0] = 1
for i in range(n-1):
    nx = [0]*6
    for j in range(1, 7):
        if j != 6:
            nx[j-1] += dp[j-1]*j/6
            nx[j] += dp[j-1]*(6-j)/6
        else:
            nx[j-1] += dp[j-1]
    dp = nx
print(dp[5])