import java.util.Scanner;

public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int a = sc.nextInt();
        int b = sc.nextInt();
        int c = sc.nextInt();
        int k = sc.nextInt();

        if (a <= b) {
            if (b <= c){
                System.out.println((int)(Math.pow(2,k)*c+a+b));
            } else {
                System.out.println((int)(Math.pow(2,k)*b+a+c));
            }
        } else {
            if (a <= c){
                System.out.println((int)(Math.pow(2,k)*c+a+b));
            } else {
                System.out.println((int)(Math.pow(2,k)*a+b+c));
            }

        }
    }
}
/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