import java.io.*;
public class Main {
    public static void main(String[] args) throws IOException{
        BufferedReader buf=new BufferedReader(new InputStreamReader(System.in));
        
        while(true){
            String str=buf.readLine();
            if(str.length()==1 && str.charAt(0)=='0'){break;}
            
            int sum=0;
            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