import java.io.*;

public class Main {
	public static void main(String[] args)throws IOException {
		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
		StringBuilder data = new StringBuilder();
		 
        while(true){
    		int sum = 0;                   //sum??????????????????????????????????¨??????¨???.???????????????????????¨?????????????????????????¨????
            String str = br.readLine();    
            int strsize = str.length();    //strsize?????????????????????????????¨???
                if(str.equals("0")) break;
                
     //??°?????????????????????????????????????????????       
                else if(strsize >= 1) {
                int i = 0;
                while(i < strsize){
                    sum += Integer.parseInt(String.valueOf(str.charAt(i))); //????????§????????????????????¨???????????????????????????
                    i++;
                }
            }
              data.append(sum).append("\n"); //?????£??????????????????????????????????????????????????????????????????????????????????????£??????????????????????????????
        
        } //while?????????
        
     //??????????????????  
        System.out.print(data);

	}
}
/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