import java.util.ArrayList;
import java.util.Scanner;
public class SumOfNumbers {
private static Scanner sc = new Scanner(System.in);
private static ArrayList<Integer> result = new ArrayList<Integer>();
public static void main(String[] args) {
while(sc.hasNextLine()){
String input = sc.nextLine();
if(input.charAt(0) == '0'){
break;
}
else{
result.add(getSum(input));
}
}
for(int i = 0; i < result.size(); i++){
System.out.println(result.get(i));
}
}
private static int getSum(String str){
int sum = 0;
for(int i = 0; i < str.length(); i++){
String c = String.valueOf(str.charAt(i));
sum = sum + Integer.parseInt(c);
}
return sum;
}
}