[NWRRC2017] Auxiliary Project

用 LED 显示器来表示数字，表示方法如下：  你必须正好点亮 $n$ 段 LED 灯，使得这些灯能够组成一些数字。现在请你求出这些一位数和的最大值。 注：“一段”LED 灯指的是一条黑色的纵向短线或一条黑色的横向线段。如，`9` 由 $6$ 断组成。 $2\le n\le2\times 10^6$。 Translated by [cmll02](https://www.luogu.com.cn/user/171487)。

Anna has just finished her course project. She has a lot of seven-segment LED displays as leftovers and a small power source. Each display consumes power proportionally to the number of lit segments, e.g . $‘9'$ consumes twice more power than $‘7'.$  Anna wonders what is the maximum possible sum of digits she is able to achieve, if her power source is able to light $n$ segments, and she wants to light exactly $n$ segments.

The single line of the input contains one integer $n$ -- the number of segments that should be lit $(2 \le n \le 10^{6}).$

Output a single integer -- the maximum possible sum of digits that can be displayed simultaneously.

4

4

7

11

6

14

Time limit: 3 s, Memory limit: 512 MB.