import java.util.*;

public class Main{
  public static void main(String[] args){
    Scanner sc = new Scanner(System.in);
    String s;
    int sum;
    while (!(s = sc.next()).equals("0")){
      sum = 0;
      for(int i = 0;i < s.length();i++){
        sum += Integer.parseInt(String.valueOf(s.charAt(i)));
      }
      System.out.println(sum);
    }
  }
}


/tmp/hf-datasets-cache/medium/datasets/42704881117311-config-parquet-and-info-qiankunmu-Project_CodeNet-896c9d36/hub/datasets--qiankunmu--Project_CodeNet_Python800_and_Java250/snapshots/c899fde44a77ba1cc14973ed3de064e4ff3aadc7/Project_CodeNet_Java250.tar.gz