#include<iostream>
#include<cmath>
using namespace std;
double p,q,r;
void read()
{
     cin>>p>>q>>r;
}
int main()
{
    read();
    if(p!=r)cout<<0<<endl;
    else
    {
        double a,b;
        a=2*p*p;;
        b=2*(p+q)*(p+q);
        a=sqrt(a);
        b=sqrt(b);
        double sum=a*b;
        printf("%.4lf\n",sum);
    }
    return 0;
}
