#include<bits/stdc++.h>
using namespace std;
int main() {
	double a, b, c;
	cin >> a >> b >> c;
	double h = (a + b + c) / 2;
	double s = sqrt(h * (h - a) * (h - b) * (h - c));
	cout << fixed << setprecision(15);
	cout << 2 * s / (a + b + c) << endl;
}