import java.util.*;
public class Main {
	public static void main(String[] args){
		Scanner sc = new Scanner(System.in);		// 整数の入力


int A= sc.nextInt();
int B= sc.nextInt();
int C= sc.nextInt();
int K= sc.nextInt();
int max=A;
int sonota=B+C;
int sum=0;

	if(max<B){
		max=B;
		sonota=A+C;
	}
	if(max<C){
		max=C;
		sonota=A+B;
	}

	for(int i=0; i<K; i++){
		sum=max*2+sonota;
		max=max*2;
	}
	System.out.println(sum);
	}

}

/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