#include <stdio.h>
#include <stdlib.h>

int main(void) {
  char S[] = "";
  int i_S = 0;

  int i = 0;

  int tmp = 0;
  int sum = 0;

  scanf("%s",S);

  i_S = atoi(S);

  tmp = i_S;
  for(i=0;i<9;i++){
    if(tmp % 10 == 0)
      sum += 10;
    else
      sum += tmp % 10;
    tmp /= 10;
  }

  printf("%d\n",sum);

  return 0;
}