import java.util.Scanner;
class Average
{
	public static void main (String [] args)
	{
		Scanner in= new Scanner(System.in); // to read in stuff

		double average;	// holds the final result
		int count=0;	// count of numbers entered
		int sum=0, currentGrade;	// hold sumn and the current entry
	
		System.out.println("Please insert your grade");
		currentGrade = in.nextInt();	// should be obvious
	
		while (currentGrade != -1)	// repeat as long as current entry is not -1
		{
			sum=currentGrade+sum;	// add current entry to the sum
			count++;		// increment count, since we have 1 more number
			System.out.println("Please insert next grade");// get the next number
			currentGrade = in.nextInt();
		}
		average= (double)sum/count;	//calculate average
		System.out.println("The average is "+average);	//print average
	
	}
}