import java.io.*;
class Main
{
    public static void main(String args[])throws IOException
    {
BufferedReader input=new BufferedReader (new InputStreamReader (System.in));
    while(true)
        {
         
        int sum=0;
        String str=input.readLine();
        if(str.equals("0"))break;
        for(int i=0;i<str.length();i++)
            {
             
            sum+=str.charAt(i)-'0';
            }
        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