import java.util.Scanner;
public class Main {
	void run(){
		Scanner s = new Scanner(System.in);
		String str = s.next();
		while(!"0".equals(str)){
			int num = 0;
			String st[] = str.split("");
			for(int i = 0;i < st.length;i++){
				num += Integer.valueOf(st[i]).intValue();
			}
			System.out.println(num);
			str = s.next();
		}
	}
	public static void main(String args[]){
		Main m = new Main();
		m.run();
	}
}
/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