A - Digit Sum 2

Time Limit: 2 sec / Memory Limit: 256 MB

### 問題文

N 以下の正の整数の 10 進法での各桁の和の最大値を求めてください。

### 制約

• 1\leq N \leq 10^{16}
• N は整数である

### 入力

N


### 出力

N 以下の正の整数の 10 進法での各桁の和の最大値を出力せよ。

### 入力例 1

100


### 出力例 1

18


### 入力例 2

9995


### 出力例 2

35


### 入力例 3

3141592653589793


### 出力例 3

137


Score : 300 points

### Problem Statement

Find the maximum possible sum of the digits (in base 10) of a positive integer not greater than N.

### Constraints

• 1\leq N \leq 10^{16}
• N is an integer.

### Input

Input is given from Standard Input in the following format:

N


### Output

Print the maximum possible sum of the digits (in base 10) of a positive integer not greater than N.

### Sample Input 1

100


### Sample Output 1

18


For example, the sum of the digits in 99 is 18, which turns out to be the maximum value.

### Sample Input 2

9995


### Sample Output 2

35


For example, the sum of the digits in 9989 is 35, which turns out to be the maximum value.

### Sample Input 3

3141592653589793


### Sample Output 3

137