def main():
    n = int(input())
    dp = [[0] * 8 for i in range(n+1)]
    dp[0][0] = 1
    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])


if __name__ == '__main__':
    main()