Operasi !Biasa 1

import java.io.*;
import java.util.*;

public class Solution {

    public static String reverse(String s) {
        String temp = "";
        for (int i = s.length() - 1; i >= 0; i--) temp += s.charAt(i);
        return temp;
    }

    public static long hitung(long n) {
        if (n < 10) return n;
        String s = reverse(String.valueOf(n));
        int len = s.length(), mid = (int)Math.ceil(len/2.0);
        String s1 = reverse(s.substring(0, mid)), s2 = reverse(s.substring(mid));
        return hitung(Long.parseLong(s1) + Long.parseLong(s2));
    }

    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        System.out.println(hitung(sc.nextLong()));
    }
}