#include <iostream>
#include <iomanip>
using namespace std;

class ElectriCharge{
private:
    double charge,distance;
    
public:
    ElectricCharge(double c,double d) {
        charge = c;
        distance = d;
    }
    void computeForce() {
        const double k =8.99e9;
        
        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.computeAndDisplay();
    return 0;
}