#include <stdio.h>

int main(void)
{
  int i = 0, sum = 0
      , tmp;
  char str[10000];

  scanf("%s", str);
  while(str[i] != '\0') i++;
  i -= 1;
  while(i >= 0){
    tmp = str[i] - '0';
    if(tmp >= 0 && tmp <= 9){
      sum += tmp;
    }
    i--;
  }
  printf("%d\n", sum);

}