Problem:
Score : 700 points

Problem Statement

Find the smallest possible sum of the digits in the decimal notation of a positive multiple of K.

Constraints

2 \leq K \leq 10^5

K is an integer.

Input

Input is given from Standard Input in the following format:

K

Output

Print the smallest possible sum of the digits in the decimal notation of a positive multiple of K.

Sample Input 1

6

Sample Output 1

3

12=6×2 yields the smallest sum.

Sample Input 2

41

Sample Output 2

5

11111=41×271 yields the smallest sum.

Sample Input 3

79992

Sample Output 3

36

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

#include<iostream>
#include<algorithm>
#include<string.h>
#include<stdlib.h>
#include<math.h>
#include<vector>
#include<deque>
#include<map>
#include<set>

using namespace std;

long long K;

long long get(long long k){
  long long ret = 0;
  for( ; k > 0; k /= 10 ){
    ret += k % 10;
  }
  return ret;
}

int main(){
  cin >> K;
  long long k = 0, min = 100;
  for( int i = 1; i <= 10000000; i++ ){
    k += K;
    long long t = get(k);
    if( t < min ){ min = t; }
  }
  cout << min << endl;
  return 0;
}