import java.util.Scanner;

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();
        sc.close();

        int max = 0;
        int ans = 0;

        max = Math.max(Math.max(a, b), c);
        if (max == a) {
            ans = b + c;
        } else if (max == b) {
            ans = a + c;
        } else {
            ans = a + b;
        }

        ans += max * 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