import java.util.Scanner;

public class Password {
    public static void main(String[] args) {
        Scanner scan = new Scanner(System.in);
      int n= Integer.parseInt(scan.nextLine());
      int sum= 0;
      for (int i=0;i<n;i++){
          int num= Integer.parseInt(scan.nextLine());
          sum += sum;
      }
      System.out.println(sum);
    }
}