n = int(input())

DP = [[0.0 for _ in range(8)] for _ in range(n + 1)]
DP[0][0] = 1.0
for i in range(n):
    for j in range(7):
        DP[i + 1][j + 1] += DP[i][j] * (6 - j) / 6
        DP[i + 1][j] += DP[i][j] * j / 6
print(DP[n][6])