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

public class Main {
    static final int MOD = 10;
    public static void main(String[] args) throws Exception {
        Scanner sc = new Scanner();
        int[] ans = new int[]{sc.nextInt() % MOD, sc.nextInt() % MOD, sc.nextInt() % MOD};
        long k = sc.nextLong() - 1;
        int[][][] matrix = new int[60][3][3];
        matrix[0] = new int[][]{{0, 1, 0}, {0, 0, 1}, {1, 1, 1}};
        for (int i = 1; i < 60; i++) {
            for (int a = 0; a < 3; a++) {
                for (int b = 0; b < 3; b++) {
                    for (int c = 0; c < 3; c++) {
                        matrix[i][a][c] += matrix[i - 1][a][b] * matrix[i - 1][b][c] % MOD;
                        matrix[i][a][c] %= MOD;
                    }
                }
            }
        }
        for (int i = 59; i >= 0; i--) {
            if (k < (1L << i)) {
                continue;
            }
            k -= (1L << i);
            int[] next = new int[3];
            for (int a = 0; a < 3; a++) {
                for (int b = 0; b < 3; b++) {
                    next[a] += matrix[i][a][b] * ans[b] % MOD;
                    next[a] %= MOD;
                }
            }
            ans = next;
        }
        System.out.println(ans[0]);
    }
}
class Utilities {
    static String arrayToLineString(Object[] arr) {
        return Arrays.stream(arr).map(x -> x.toString()).collect(Collectors.joining("\n"));
    }
    
    static String arrayToLineString(int[] arr) {
        return String.join("\n", Arrays.stream(arr).mapToObj(String::valueOf).toArray(String[]::new));
    }
}
class Scanner {
    BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
    StringTokenizer st = new StringTokenizer("");
    StringBuilder sb = new StringBuilder();
    
    public Scanner() throws Exception {
        
    }
    
    public int nextInt() throws Exception {
        return Integer.parseInt(next());
    }
    
    public long nextLong() throws Exception {
        return Long.parseLong(next());
    }
    
    public double nextDouble() throws Exception {
        return Double.parseDouble(next());
    }
    
    public int[] nextIntArray() throws Exception {
        return Stream.of(br.readLine().split(" ")).mapToInt(Integer::parseInt).toArray();
    }
    
    public String next() throws Exception {
        while (!st.hasMoreTokens()) {
            st = new StringTokenizer(br.readLine());
        }
        return st.nextToken();
    }
    
}