import static java.lang.System.*;
import java.util.*;
 
public class Main {
	static Scanner sc = new Scanner(System.in);
	public static void main(String[] args) {
		int a=sc.nextInt(), b=sc.nextInt(), c=sc.nextInt(), k=sc.nextInt();
		int total = a+b+c;
		int max = max(a,b,c);
		int pow = (int)Math.pow(2,k);
		out.println((total-max)+max*pow);
	}
	
	static int max(int... ar) {
		Arrays.sort(ar);
		return ar[ar.length-1];
	}
}
/tmp/hf-datasets-cache/medium/datasets/42704881117311-config-parquet-and-info-qiankunmu-Project_CodeNet-896c9d36/hub/datasets--qiankunmu--Project_CodeNet_Python800_and_Java250/snapshots/c899fde44a77ba1cc14973ed3de064e4ff3aadc7/Project_CodeNet_Java250.tar.gz