1.1-7

import java.util.Scanner;

public class Main {

    public static void main(String[] args) {
    Scanner sc = new Scanner(System.in);
    String[] st = sc.nextLine().split(" ");
    double first = Double.parseDouble(st[0]);
    double second = Double.parseDouble(st[1]);
    System.out.println(0.5*(first+second+Math.abs(first-second)));
    }
}