import java.util.*;

public class Main {
    static int next(int a){
        int p = (a/100)%10, q = (a/10)%10, r = a%10;
        int s = (p+q+r)%10;
        return 100*q+10*r+s;
    }
    public static void main(String[] args) throws Exception{
        final ContestScanner sc = new ContestScanner();
        final ContestPrinter pr = new ContestPrinter();
        
        int p = sc.nextInt()%10, q = sc.nextInt()%10, r = sc.nextInt()%10;
        int a = 100*p+10*q+r;

        int[][] dp = new int[1000][62];
        for(int i=0; i<1000; i++) dp[i][0] = next(i);
        for(int d=1; d<62; d++)for(int i=0; i<1000; i++) dp[i][d] = dp[dp[i][d-1]][d-1];
        
        long K = sc.nextLong()-3;
        for(int d=0; d<62; d++) if((K&(1L<<d)) != 0){
            a = dp[a][d];
        }

        pr.println(a%10);
        pr.close();
    }
}


class ContestScanner {
    private final java.io.InputStream in;
    private final byte[] buffer = new byte[1024];
    private int ptr = 0;
    private int buflen = 0;

    private static final long LONG_MAX_TENTHS = 922337203685477580L;
    private static final int LONG_MAX_LAST_DIGIT = 7;
    private static final int LONG_MIN_LAST_DIGIT = 8;

    public ContestScanner(java.io.InputStream in){
        this.in = in;
    }
    public ContestScanner(){
        this(System.in);
    }
 
    private boolean hasNextByte() {
        if (ptr < buflen) {
            return true;
        }else{
            ptr = 0;
            try {
                buflen = in.read(buffer);
            } catch (java.io.IOException e) {
                e.printStackTrace();
            }
            if (buflen <= 0) {
                return false;
            }
        }
        return true;
    }
    private int readByte() { 
        if (hasNextByte()) return buffer[ptr++]; else return -1;
    }
    private static boolean isPrintableChar(int c) {
        return 33 <= c && c <= 126;
    }
    public boolean hasNext() {
        while(hasNextByte() && !isPrintableChar(buffer[ptr])) ptr++;
        return hasNextByte();
    }
    public String next() {
        if (!hasNext()) throw new java.util.NoSuchElementException();
        StringBuilder sb = new StringBuilder();
        int b = readByte();
        while(isPrintableChar(b)) {
            sb.appendCodePoint(b);
            b = readByte();
        }
        return sb.toString();
    }
 
    public long nextLong() {
        if (!hasNext()) throw new java.util.NoSuchElementException();
        long n = 0;
        boolean minus = false;
        int b = readByte();
        if (b == '-') {
            minus = true;
            b = readByte();
        }
        if (b < '0' || '9' < b) {
            throw new NumberFormatException();
        }
        while (true) {
            if ('0' <= b && b <= '9') {
                int digit = b - '0';
                if (n >= LONG_MAX_TENTHS) {
                    if (n == LONG_MAX_TENTHS) {
                        if (minus) {
                            if (digit <= LONG_MIN_LAST_DIGIT) {
                                n = -n * 10 - digit;
                                b = readByte();
                                if (!isPrintableChar(b)) {
                                    return n;
                                } else if (b < '0' || '9' < b) {
                                    throw new NumberFormatException(
                                        String.format("%d%s... is not number", n, Character.toString(b))
                                    );
                                }
                            }
                        } else {
                            if (digit <= LONG_MAX_LAST_DIGIT) {
                                n = n * 10 + digit;
                                b = readByte();
                                if (!isPrintableChar(b)) {
                                    return n;
                                } else if (b < '0' || '9' < b) {
                                    throw new NumberFormatException(
                                        String.format("%d%s... is not number", n, Character.toString(b))
                                    );
                                }
                            }
                        }
                    }
                    throw new ArithmeticException(
                        String.format("%s%d%d... overflows long.", minus ? "-" : "", n, digit)
                    );
                }
                n = n * 10 + digit;
            }else if(b == -1 || !isPrintableChar(b)){
                return minus ? -n : n;
            }else{
                throw new NumberFormatException();
            }
            b = readByte();
        }
    }
    public int nextInt() {
        long nl = nextLong();
        if (nl < Integer.MIN_VALUE || nl > Integer.MAX_VALUE) throw new NumberFormatException();
        return (int) nl;
    }
    public double nextDouble() {
        return Double.parseDouble(next());
    }
 
    public long[] nextLongArray(int length){
        long[] array = new long[length];
        for(int i=0; i<length; i++) array[i] = this.nextLong();
        return array;
    }
    public long[] nextLongArray(int length, java.util.function.LongUnaryOperator map){
        long[] array = new long[length];
        for(int i=0; i<length; i++) array[i] = map.applyAsLong(this.nextLong());
        return array;
    }
    public int[] nextIntArray(int length){
        int[] array = new int[length];
        for(int i=0; i<length; i++) array[i] = this.nextInt();
        return array;
    }
    public int[] nextIntArray(int length, java.util.function.IntUnaryOperator map){
        int[] array = new int[length];
        for(int i=0; i<length; i++) array[i] = map.applyAsInt(this.nextInt());
        return array;
    }
    public double[] nextDoubleArray(int length){
        double[] array = new double[length];
        for(int i=0; i<length; i++) array[i] = this.nextDouble();
        return array;
    }
    public double[] nextDoubleArray(int length, java.util.function.DoubleUnaryOperator map){
        double[] array = new double[length];
        for(int i=0; i<length; i++) array[i] = map.applyAsDouble(this.nextDouble());
        return array;
    }
 
    public long[][] nextLongMatrix(int height, int width){
        long[][] mat = new long[height][width];
        for(int h=0; h<height; h++) for(int w=0; w<width; w++){
            mat[h][w] = this.nextLong();
        }
        return mat;
    }
    public int[][] nextIntMatrix(int height, int width){
        int[][] mat = new int[height][width];
        for(int h=0; h<height; h++) for(int w=0; w<width; w++){
            mat[h][w] = this.nextInt();
        }
        return mat;
    }
    public double[][] nextDoubleMatrix(int height, int width){
        double[][] mat = new double[height][width];
        for(int h=0; h<height; h++) for(int w=0; w<width; w++){
            mat[h][w] = this.nextDouble();
        }
        return mat;
    }
 
    public char[][] nextCharMatrix(int height, int width){
        char[][] mat = new char[height][width];
        for(int h=0; h<height; h++){
            String s = this.next();
            for(int w=0; w<width; w++){
                mat[h][w] = s.charAt(w);
            }
        }
        return mat;
    }
}

class ContestPrinter extends java.io.PrintWriter{
    public ContestPrinter(java.io.PrintStream stream){
        super(stream);
    }
    public ContestPrinter(){
        super(System.out);
    }
    
    private static String dtos(double x, int n) {
        StringBuilder sb = new StringBuilder();
        if(x < 0){
            sb.append('-');
            x = -x;
        }
        x += Math.pow(10, -n)/2;
        sb.append((long)x);
        sb.append(".");
        x -= (long)x;
        for(int i = 0;i < n;i++){
            x *= 10;
            sb.append((int)x);
            x -= (int)x;
        }
        return sb.toString();
    }

    @Override
    public void print(float f){
        super.print(dtos(f, 20));
    }
    @Override
    public void println(float f){
        super.println(dtos(f, 20));
    }
    @Override
    public void print(double d){
        super.print(dtos(d, 20));
    }
    @Override
    public void println(double d){
        super.println(dtos(d, 20));
    }
    
    

    public void printArray(int[] array, String separator){
        int n = array.length;
        if(n==0){
            super.println();
            return;
        }
        for(int i=0; i<n-1; i++){
            super.print(array[i]);
            super.print(separator);
        }
        super.println(array[n-1]);
    }
    public void printArray(int[] array){
        this.printArray(array, " ");
    }
    public void printArray(int[] array, String separator, java.util.function.IntUnaryOperator map){
        int n = array.length;
        if(n==0){
            super.println();
            return;
        }
        for(int i=0; i<n-1; i++){
            super.print(map.applyAsInt(array[i]));
            super.print(separator);
        }
        super.println(map.applyAsInt(array[n-1]));
    }
    public void printArray(int[] array, java.util.function.IntUnaryOperator map){
        this.printArray(array, " ", map);
    }

    public void printArray(long[] array, String separator){
        int n = array.length;
        if(n==0){
            super.println();
            return;
        }
        for(int i=0; i<n-1; i++){
            super.print(array[i]);
            super.print(separator);
        }
        super.println(array[n-1]);
    }
    public void printArray(long[] array){
        this.printArray(array, " ");
    }
    public void printArray(long[] array, String separator, java.util.function.LongUnaryOperator map){
        int n = array.length;
        if(n==0){
            super.println();
            return;
        }
        for(int i=0; i<n-1; i++){
            super.print(map.applyAsLong(array[i]));
            super.print(separator);
        }
        super.println(map.applyAsLong(array[n-1]));
    }
    public void printArray(long[] array, java.util.function.LongUnaryOperator map){
        this.printArray(array, " ", map);
    }    
}