/******************************************************************************
 * This program computes the median of a list of float values on STDIN.
 * 
 * Copyright © 2021 Richard Lesh.  All rights reserved.
 *****************************************************************************/

import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;
import org.pureprogrammer.Utils;

public class MedianFilter {

    public static void main(String[] args) {
        String line;
        double d;
        int count = 0;
        List<Double> values = new ArrayList<>();

        while ((line = Utils.getline()) != null) {
            line = Utils.trim(line);
            try {
                d = Double.parseDouble(line);
                values.add(d);
                ++count;
            } catch (Exception ex) {
                if (Utils.cpLength(line) > 0) {
                    System.out.println(Utils.join("", "Can't parse input: ", line));
                }
            }
        }

        values = Utils.sort(values);
        if (count > 0) {
            double median;
            if (count % 2 == 1) {
                median = values.get((count - 1) / 2);
            } else {
                int middle = count / 2;
                median = (values.get(middle) + values.get(middle - 1)) / 2.0;
            }
            System.out.println(Utils.format("{0:g}", median));
        }
    }
}