Josh loves solving problems. However, solving problems takes a lot of time, so he will sometimes batch problems together, which allows him to solve them quicker. He will do it according to the following rules:

• Every 2 problems take him 1 minute to solve (rounded down).
• Every 7 problems take him 1 less minute to solve than usual.

Some examples:

• Solving $8$ problems takes Josh $\frac{8}{2}-\lfloor \frac{8}{7}\rfloor =4-1=3$ minutes. It takes him $4$ minutes to solve the problems usually. However, since he's solved $8$ problems, and every $7$ problems take $1$ less minute, he will only take $4-1=3$ minutes.
• Solving $7$ problems takes Josh $\lfloor \frac{7}{2}\rfloor -1=2$ minutes in total.
• Solving $1$ problem takes Josh $0-0=0$ minutes.

Josh has only $T$ minutes to solve as many problems as possible. Can you determine the maximum number of problems he can solve?

Input Specification

The first line will contain the integer $T$ $(1\le T\le {10}^{14})$.

Output Specification

Output the maximum number of problems Josh can solve in $T$ minutes.

Subtasks

Subtask 1 [37%]

$T\le {10}^6$

Subtask 2 [63%]

No additional constraints.

Sample Input for Subtask 1

5

Sample Output for Subtask 1

15

Explanation for Sample for Subtask 1

Solving $15$ problems takes him $\lfloor \frac{15}{2}\rfloor -\lfloor \frac{15}{7}\rfloor =7-2=5$ minutes, which is exactly the amount of time he has.

Sample Input for Subtask 2

1000000007

Sample Output for Subtask 2

2800000021