#include<iostream>
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 computeForce() {
        if (charge<=0||distance<=0) {
            cout<<"Invalid input";
            return 0;
        }
        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;
}