import java.util.*;

public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int a=sc.nextInt(),b=sc.nextInt(),c=sc.nextInt(),k=sc.nextInt();
        System.out.println((int)(a+b+c+Math.max(a,Math.max(b,c))*(Math.pow(2,k)-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