Problem Description

JOI has $A$ yen. Find the maximum number of pencils he can buy when $1$ pencil costs $5$ yen.

Constraints

• $1 \le A \le 100$.
• $A$ is an integer.

Input

The input is given in the following format:
$A$

Output

Output the maximum number of pencils JOI can buy, omitting the unit.

Do not output anything other than the answer. (Do not output prompt messages for input, etc.)

For the answer format, you may also refer to the practice problems and their sample solutions.

Sample Input 1

9

Sample Output 1

1

• Since $1$ pencil costs $5$ yen, JOI can buy $1$ pencil.
• Since $2$ pencils cost $10$ yen, JOI cannot buy $2$ or more pencils.

Therefore, output $1$.

Sample Input 2

10

Sample Output 2

2

• Since $2$ pencils cost $10$ yen, JOI can buy $2$ pencils.
• Since $3$ pencils cost $15$ yen, JOI cannot buy $3$ or more pencils.

Therefore, output $2$.

Sample Input 3

3

Sample Output 3

0

• JOI cannot buy even $1$ pencil.

Therefore, output $0$.

Sample Input 4

100

Sample Output 4

20

• Since $20$ pencils cost $100$ yen, JOI can buy $20$ pencils.
• Since $21$ pencils cost $105$ yen, JOI cannot buy $21$ or more pencils.

Therefore, output $20$.