#include<iostream>
#include<vector>
#include<math.h>
#include<iomanip>
using namespace std;

int main() {
	long double a,b,c;cin>>a>>b>>c;
	long double s = (a+b+c) / 2.0;
	long double S = sqrt(s*(s-a)*(s-b)*(s-c));
	long double ans = 2*S / (a+b+c);
	cout << setprecision(20) << fixed;
	cout << ans << endl;
}