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

public class Main {
    public static void main(String[] args) throws Exception {
        Scanner sc = new Scanner();
        int current = sc.nextInt() % 10 * 100 + sc.nextInt() % 10 * 10 + sc.nextInt() % 10;
        long k = sc.nextLong();
        int[] place = new int[1000];
        int count = 0;
        int interval = 0;
        for (int i = 4; i <= 1004; i++) {
            if (i == k) {
                System.out.println((current / 100 + current % 100 / 10 + current % 10) % 10);
                return;
            }
             if (place[current] != 0) {
                count = place[current];
                interval = i - place[current];
                break;
            }
            
            place[current] = i;
            current = getNext(current);
        }
        long mod = (k - count) % interval;
        int ans = 0;
        for (int i = 0; i < 1000; i++) {
            if (count + mod == place[i]) {
                System.out.println((i / 100 + i % 100 / 10 + i % 10) % 10);
                return;
            }
        }
    }
    
    static int getNext(int x) {
        int count = x / 100 + x % 100 / 10 + x % 10;
        count %= 10;
        return (x * 10 + count) % 1000;
    }
}
class Scanner {
    BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
    StringTokenizer st = new StringTokenizer("");
    
    public Scanner() throws Exception {
        
    }
    
    public int nextInt() throws Exception {
        return Integer.parseInt(next());
    }
    
    public long nextLong() throws Exception {
        return Long.parseLong(next());
    }
    
    public String next() throws Exception {
        if (!st.hasMoreTokens()) {
            st = new StringTokenizer(br.readLine());
        }
        return st.nextToken();
    }
}