题解 | #上下取整#

import java.util.Scanner;
import java.lang.Math;

public class Main{
    public static void main(String[] args){
        Scanner scan = new Scanner(System.in);
        int a = scan.nextInt();
        int b = scan.nextInt();
        int c = scan.nextInt();
        double d = (a + b + c) / 3.0;
        System.out.println(String.format("%.6f",d));
    }    
}