#include <stdio.h>
int main() {
  char str[10000] = {'\0'};
  scanf("%s", str);
  int i, ans;
  for (i = 0; i < 10000; i++) {
    switch (str[i]) {
      case '1': ans += 1;
                break;
      case '2': ans += 2;
                break;
      case '3': ans += 3;
                break;
      case '4': ans += 4;
                break;
      case '5': ans += 5;
                break;
      case '6': ans += 6;
                break;
      case '7': ans += 7;
                break;
      case '8': ans += 8;
                break;
      case '9': ans += 9;
                break;
    }
    if (str[i] == '\0') {
      break;
    }
  }
  printf("%d\n", ans);
  return 0;
}