Problem Description

Score: $ 100 $ points

Tsukukoma Pakken has grown to become a major national corporation by the year $ X $, and "Pakken Gasshuku X" is to be held.

Now, "Pakken Gasshuku X" must invite several groups. Mr. T, the person in charge, decided to determine the number of groups to invite according to the following rules:

• Considering the current year $ X $ in its decimal notation.
• The number of groups to invite is the maximum digit appearing in $ X $.

Please find the number of groups Mr. T will invite.

Input Format

The input is given from the standard input in the following format:

$ X $

Output Format

Output the number of groups to invite in one line.

Do not forget to add a newline at the end of the output.

Sample Input and Output

Sample Input #1

2021

Sample Output #1

2

Sample Input #2

2403

Sample Output #2

4

Sample Input #3

1736

Sample Output #3

7

Notes/Hints

None

见题面 Input 部分

见题面 Output 部分