import java.util.*;
import java.util.stream.*;
import java.lang.*;
import java.io.*;

class Ideone
{
	public static void main (String[] args) throws java.lang.Exception
	{
		int[] numbers = {5, 8, 12, -18, -54, 84, -35, 17, 37};
		double average = IntStream.of(numbers).average().getAsDouble();
		System.out.println(average);
	}
}