#include<bits/stdc++.h>
using namespace std;
int main() {
	long double a,b,c;
	cin >> a >> b >> c ;
	if(b + c > a && a + c > b && a + b > c){
		long double p=(a+b+c)/2;
		cout<<fixed<<setprecision(2)<<(long double)sqrt(p*(p-a)*(p-b)*(p-c));
	}
	else cout<<"No Solution.";
}