import java.util.Scanner;
public class Main {
	public static void main(String[] args) {
		Scanner scan = new Scanner(System.in);
		int A = scan.nextInt();
		int B = scan.nextInt();
		int C = scan.nextInt();
		int K = scan.nextInt();
		int max;
		if(A <= B) {
			if(B <= C) {
				max = C;
			}else {
				max = B;
			}
		}else {
			if(A <= C) {
				max = C;
			}else {
				max = A;
			}
		}
		if(max == A) {
			for(int i = 0;i < K;i++) {
				max *= 2;
			}
			max = max + B + C;
		}else if(max == B) {
			for(int i = 0;i < K;i++) {
				max *= 2;
			}
			max = max + A + C;
		}else {
			for(int i = 0;i < K;i++) {
				max *= 2;
			}
			max = max + B + A;
		}
		System.out.println(max);
	}
}
/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