import java.util.*;
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();
 
   int[] re = {A,B,C};
   Arrays.sort(re);
   
   int d =1;
   for(int i =0;i<K;i++) d*=2;
 
   System.out.println(re[0]+re[1]+re[2]*d);
 }
}
/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