import java.util.Scanner;
public class Main{
    public static void main(String[]args) {
        Scanner sc = new Scanner(System.in);
        while(true){
        String x = sc.next();
        int y = x.length();
            if (x.equals("0")) {
                break;
            } else {
                int sum = 0;
                for (int i = 0; i < y; i++) {
                    char c = x.charAt(i);
                    int n = c - '0';
                    sum = sum + n;
                }
                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