import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.util.Arrays;



public class Main{
	public static void main(String[] args){


		BufferedReader reader=new BufferedReader(new InputStreamReader(System.in));
		String s;
		int sum;
		try{
		while(true){
			sum=0;
			String[] s_array;//???????????§?????????1???????????????????????????????????????????????????????????????
			s=reader.readLine();
			s_array=s.split("");
			int[] s_num=new int[s_array.length];
			Arrays.fill(s_num, 0);
			for(int i=0;i<s_array.length;i++){
				s_num[i]=Integer.parseInt(s_array[i]);
				sum+=s_num[i];
			}
			if(sum==0)break;
			System.out.println(sum);
		}




		}catch(IOException e){
			System.out.println(e);
		}

	}
}
/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