Auxiliary Project

문제

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’.

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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.

입력

The single line of the input contains one integer n — the number of segments that should be lit (2 ≤ n ≤ 10⁶).

출력

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

힌트

In the first example, a single ‘4’ should be displayed (‘7’ has greater value, but has only three segments). In the second example ‘4’ and ‘7’ should be displayed, in the third one — two ‘7’s.