#include<iostream>
#include<cmath>
#include <iomanip>
using namespace std;

int main()
{
	cout.precision(4);
	double h, w = 0;
	cin >> h;
	cin >> w;
	double b = max(h, w);
	double a = min(w, h);
	double c = min(a, max(b/3, a/2));
	cout << fixed << c;
}