import java.util.*;

class Main{
	public static void main(String args[]) throws Exception{
		Scanner sc = new Scanner(System.in);
		long a[] = new long[3];
		for(int i = 0; i < 3; i++) a[i] = sc.nextLong();
		int K = sc.nextInt();
		Arrays.sort(a);
		for(int i = 1; i <= K; i++) a[2] *= 2;
		long ans = 0;
		for(int i = 0; i < 3; i++) ans += a[i];
		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