#include <iostream>
using namespace std;
int main() {
    string s;
    while ((cin >> s) && (s != "0")) {
        int c = 0;
        for (int i=0; i<s.length(); i++)
            c += (s[i]-'0');
        cout << c << endl;
    }
    return 0;
}

import java.io.*;
public class My {
    public static void main(String[] args) {
        BufferedReader br = new BufferedReader(new
                InputStreamReader(System.in));
        while (true) {
            int x = 0;
            try {
                String s = br.readLine();
                x = Integer.parseInt(s);
            }
            catch (Exception e) {
                e.printStackTrace();
            }
            if (x == 0)
                break;
            int sum = 0;
            while(x > 0) {
                sum += x%10;
                x /= 10;
            }
            System.out.println(sum);
        }
    }
}