题解 | #求平均数#

import java.util.Scanner;

public class Main {

    public static void main(String[] args) {
        Scanner scan = new Scanner(System.in);

        double avg = 0;
        double sum = 0;
        int num = 0;

        //write your code here......
        while(true){
            double d = scan.nextDouble();
            if(d < 0){
                break;
            }else{
                num++;
                sum += d;
            }
        }

        avg = sum / num;
        
        System.out.println(String.format("%.2f",avg));
        
    }
}