#include <bits/stdc++.h>

using namespace std;

int main() {
    double a, b;
    cin >> a >> b;
    double x = max(a, b);
    double y = min(a, b);

    double ans;
    if (x == y) {
        ans = sqrt(2) * a;
    } else {
        ans = sqrt((x + y) * (x - y));
    }

    printf("%.7lf\n", ans);
    return 0;
}