import java.util.*;
public class Main {
	public static void main(String[] args){
		Scanner sc = new Scanner(System.in);
    
		// 整数の入力
        int[] list = new int[3];
        for(int i = 0; i < 3; i++) {
          list[i] = sc.nextInt();
        }
        Arrays.sort(list);
      
        int k = sc.nextInt();
      
        for(int i = 0; i < k; i++) {
          list[2] *= 2;
        }
        int ans = 0;
        for(int i = 0; i < list.length; i++) {
          ans += list[i];
        }
    
		// 出力
		System.out.println(ans);
	}
}
/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