#include <iostream>
#include <iomanip>//小数点出力用
#include <cmath>
using namespace std;
int main() {
	double A, B, C;
	cin >> A >> B >> C;
	double S = 1;
	S *= (A + B + C) / 2;
	S *= (- A + B + C) / 2;
	S *= (A - B + C) / 2;
	S *= (A + B - C) / 2;
	S = sqrt(S);
	double P = A + B + C;
	cout << fixed << setprecision(15) << (double)2 * S / P;
	return 0;
}