import java.util.*;
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();
		int Ans = 0;
		int Max = Math.max(A, B);
		Max = Math.max(Max, C);
		double pow = Math.pow(2, K);
		if (Max == A) {
			Ans = (A * (int)pow) + B + C;
		} else if (Max == B) {
			Ans = (B * ((int)pow)) + A + C;
		} else {
			Ans = (C * ((int)pow)) + A + B;
		}
		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