#include <stdio.h>

int main(){
  int n, i=0, sum=0;
  char s[10001];
  scanf("%s", s);
  while(s[i] != '\0'){
    if(s[i]>='0' &&'9'>=s[i]){
      sum += s[i]-'0';
    }
    i++;
  }
  printf("%d\n", sum);
  return 0;
}