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);
    int n=0,i=0;
    double s=0;
    while((n=scan.nextInt())>=0){
        s=s+n;
        i++;
    }
    System.out.println(String.format("%.2f",s/i));
}

}