import java.util.Arrays;
import java.util.Scanner;

public class Main{

	static Scanner s=new Scanner(System.in);

	public static void main(String __[]){
		while(true) {
			input();
			if(in.charAt(0)=='0') return;
			solve();
		}
	}

	static String in;
	private static void input(){
		in=s.next();
	}

	private static void solve(){
		int[] x=new int[in.length()];
		for(int i=0;i<in.length();i++)
			x[i]=in.charAt(i)-'0';
		System.out.println(Arrays.stream(x).parallel().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