#include <iostream>
using namespace std;

double p,q,r;

int main() {
    cin>>p>>q>>r;

    if (p-r>0.001 || r-p > 0.001) {
        cout<<0<<"\n";
        return 0;
    }

    double s=2*p*(p+q);
    printf("%.4lf\n",s);
}
