import java.io.BufferedReader;
import java.io.InputStreamReader;

public class Main {
	public static void main(String[] args) throws Exception {
		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
		String[] sa = br.readLine().split(" ");
		int a = Integer.parseInt(sa[0]);
		int b = Integer.parseInt(sa[1]);
		br.close();

		if (a == b) {
			System.out.println(0);
			return;
		}

		double ans = 0;
		double eps = (b - a) / 100000.0;
		for (double i = a; i < b; i+=eps) {
			ans -= (i - a) * (i - b) * eps;
		}
		System.out.println(ans);
	}
}