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

class ElectriCharge {
private:
    double charge, distance;
    
public:
    ElectricCharge(double c, double d) {
        charge = c;
        distance = d;
    }
    
    void computeAndDisplay() {
        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;
}