#include <bits/stdc++.h>

using namespace std;

int main(){
    ios::sync_with_stdio;

    double h;
    double w;
    cin >> h >> w;

    if (h > w) {
        double temp = h;
        h = w;
        w = temp;
    }

    double ans = h/2.0;
    if (w/3.0 <= h && w/3 > ans) ans = w/3.0;
    if (3*h <= w) ans = h;

    cout << ans << "\n";
}