import java.util.*;

public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        double a = sc.nextInt();
        double b = sc.nextInt();
        double aResult = Math.pow(a, 3) / 3 - (a + b) * Math.pow(a, 2) / 2 + a * b * a;
        double bResult = Math.pow(b, 3) / 3 - (a + b) * Math.pow(b, 2) / 2 + a * b * b;
        System.out.println(aResult - bResult);
    }
}