import static java.lang.Math.max;
import java.util.Scanner;
class Main
{
	public static void main (String[] args)
	{
		double tmp = 0, ans = 0;
		Scanner scanner = new Scanner(System.in);
		double h = scanner.nextDouble();
		double w = scanner.nextDouble();
		if(w < h) {
			tmp = h;
			h = w;
			w = tmp;
		}
		if(w >= 3 * h) {
			ans = h;
		}
		else {
			 ans = Math.max(h/2, w/3);
		}
		System.out.printf("%.4f", ans);
	}
}