import java.util.*;


public class Main {
	public static void main(String[] args){
		Scanner sc = new Scanner(System.in);
		int n = sc.nextInt();

		int[] numArray = new int[n];

		for(int i = 0; i < n; i++){
			numArray[i] = sc.nextInt();
        }
        
        if( n > 1){
            Arrays.sort(numArray);
            double value = (numArray[0] + numArray[1]) / 2;
            for(int i = 2; i < n; i++){
                value = (value + numArray[i]) / 2;
            }

            System.out.println(value);

        } else {
            System.out.println(numArray[0]);
        }

	}
}