#include <iostream>
#include <iomanip>
using namespace std;
class ElectricCharge {
    private:
    double charge;
    double distance;
    const double k=8.99e9
    public:
    ElectricCharge(double c,double d){
        charge = c;
        distance = d;
    }
    void computerForce(){
        if (charge<=0 || distance <=0){
            cout<<"Invalid input";
            return;
        }
        double force=k*charge*charge/(distance*distance);
        cout<<fixed<<setprecision(3)<<force;
    };
};
int main(){
    double charge , distance;
    cin>>charge>>distance;
    ElectricCharge obj(charge,distance);
    obj.computeforce();
    return 0;
}