import java.util.*;
import java.io.*;

class Avg {
    public static void main(String[] args) throws FileNotFoundException {
        String name = args[0];
        String filename = args[1];
        Scanner s = new Scanner(new File(filename));
        while (s.hasNextLine()) {
            String line = s.nextLine();
            String[] parts = line.split(":");
            if (parts[0].equals(name)) {
                String[] grades = parts[1].split(" ");  // "4", "2", "5", "1", "3"
                int[] gradesNum = new int[grades.length];
                for (int i = 0; i < grades.length; i++)
                    gradesNum[i] = Integer.parseInt(grades[i]);
                int sum = 0;
                for (int i = 0; i < grades.length; i++)
                    sum += gradesNum[i];
                double avg = sum;
                avg = avg / grades.length;
                System.out.println(avg);
            }
        }
    }
}