#include <stdio.h>
#include <ctype.h>

int main(void)
{
  char nums[100001];
  int result = 0;

  scanf("%s", nums);
  for (int i = 0; nums[i] != '\0'; ++i) {
    if (isdigit(nums[i])) {
      result += nums[i] - '0';
    }
  }
  printf("%d\n", result);
  return 0;
}