#include <iostream>
#include <algorithm>
#include <cmath>
#include <iomanip>
using namespace std;
int main() {
double h, w, ans = 0;
cin >> h >> w;
if (w < h) {
swap (w, h);
}
ans = ( w >= 3 * h ? h : max (h / 2, w / 3) );
cout << fixed << setprecision(4) << ans;
return 0;
}
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