#include <iostream>

using namespace std;

int main()
{
    double n,h,v;
    cin>>n;
    cin>>h;
    cin>>v;


    if( h>=n/2 && v>=n/2 )
    {
        cout<< v*h*4<<endl;

    }
    else if(v>=n/2 && h<=n/2)
    {
        cout<<v*(n-h)*4<<endl;


        }else if(v<=n/2 && h>=n/2) {


            cout<<h*(n-v)*4<<endl;


            }else if(v<=n/2 && h<=n/2){

                cout<<(n-v)*(n-h)*4<<endl;

            }

                    return 0;
            }