import java.util.*;

//Takes in an arbitrary number of integers and outputs their mean

public class MeanArbitrary
{
	public static void main ( String args[])
	{
		Scanner console = new Scanner (System.in);
		
		System.out.print("Please give a series of integers terminated by a -1: ");
		
		int sum = 0;
		int countUsersInputs = 0;
		int usersInput = console.nextInt();
		
		while ( usersInput != -1)
		{
			sum += usersInput;
			++countUsersInputs;
			usersInput = console.nextInt();
		}
		
		System.out.println("The mean of your numbers is: " + (double)(sum) / countUsersInputs);
	}
}