N = int(input())
if N >= 1000:
    exit(print('0.99999999999999'))

dp = [[0] * (1<<6) for _ in range(N + 1)]
dp[0][0] = 1
for i in range(N):
    for j in range(1<<6):
        val = dp[i][j]
        if val == 0:
            continue
        for k in range(6):
            dstj = j | 1<<k
            dp[i + 1][dstj] += val/6

print('{:.10f}'.format(dp[-1][-1]))