package demo1004;

import java.text.DecimalFormat;
import java.util.Scanner;

public class Main {

    /**
     * @param args
     */
    public static void main(String[] args) {
        Scanner input = new Scanner(System.in);
        float value = 0;
        float number = 0;
        for(int i =0;i<12;i++)
        {
            number = Float.valueOf(input.nextLine()).floatValue();
            value+=number;
        }
        DecimalFormat df = new DecimalFormat(".00");
        
        float result = (float) ((float)value/12.0);
        String str = df.format(result);
        System.out.println("$"+str);
        
        

    }

}