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

class ElectricCharge {
    private:
    double charge;
    double distance;
    
public:
    Electric charge(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 << force;
    }
};
 int main() {
     double charge, distance;
     cin >> charge >> distance;
     
     ElectricCharge obj(charge, distance);
     obj.computeForce();
     
     return 0;
 }