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(),
			ans = 0;
		if(a >= b && a >= c) {
			ans = b + c + a * (int)Math.pow(2, k);
		} else if(b >= a && b >= c) {
			ans = a + c + b * (int)Math.pow(2, k);
		} else {
			ans = a + b + c * (int)Math.pow(2, k);
		}
		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