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