#include <stdio.h>

int main(void)
{
  int i, total, extraction;
  char S[10001];

  total = i = 0;
  scanf("%s", S);
  while(S[i] != '\0'){
    extraction = S[i++] - '0';
    if(extraction >= 0 && extraction < 10){
      total += extraction;
    }
  }
  printf("%d\n", total);

  return 0;
}