Problem:
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

Solution in C++14 (GCC 5.4.1) (judge verdict: Wrong Answer)

#include <bits/stdc++.h>
int main(void)
{
  char n[17];
  int max = 0;
  std::cin >> n;
  for(int i = 0; i < std::strlen(n); i++){
    if((int)n[i] - '0' > 0){
      int sum = (int)n[i] - '1';
      for(int j = i + 1; j < std::strlen(n); j++) sum += 9;
      max = std::max(max, sum);
    }
  }
  std::cout << max << std::endl;
  return 0;
}