import java.util.*;

public class Main{
  public static void main(String[] args){
    Scanner scanner = new Scanner(System.in);
    while(true){
    String a = scanner.next();
    if(a.equals("0")) break;
    int sum = 0;
    for(int i = 0; i < a.length(); i++){
      char num = a.charAt(i);
      sum += Integer.parseInt("" + num);
    }
    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