import java.io.*;
 
class Main{
    public static void main(String[] args)throws IOException{
		long sum;
		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));

		while(true){
			sum = 0;
			String inp = br.readLine();
			if(inp.equals("0")){
				break;
			}
			char[] ch = inp.toCharArray();
			for(char c : ch){
				sum += Character.getNumericValue(c);
			}
			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