ZOJ-1115

import java.util.Scanner;public class Main{public static void main(String[] args){Scanner sc = new Scanner(System.in);while (true){String s = sc.nextLine();if ("0".equals(s.trim())){break;}System.out.println(root(s));}}static int root(String s){if (s.length() == 1){return Integer.parseInt(s);}else{char[] chars = s.toCharArray();int sum = 0;for (char c : chars){sum += c - 48;}return root(sum + "");}}}