#include<bits/stdc++.h>
using namespace std;
using ll =long long;

#include<atcoder/dsu>
using namespace atcoder;


void solve(){
	double A,B,C;
	cin>>A>>B>>C;
	double S=(A+B+C)/2;
	double ar=sqrt(S)*sqrt(S-A)*sqrt(S-B)*sqrt(S-C);
	double d=A+B+C;
	cout<<fixed<<setprecision(15)<<ar/d*2.0<<endl;
}

int main(){
    ios::sync_with_stdio(false);
    cin.tie(nullptr);


	int T=1;
	// cin>>T;
	while(T--)solve();
	
}