#include <iostream>
#include <iomanip>

using namespace std;

class ElectriCharge {
private:
    double charge;
    double distance;
    
public:
    ElectricCharge(double q, double d) {
        charge = q;
        distance = d;
    }
    void computeAndDisplay() {
        if (charge<=0||distance<=0) {
            cout <<"Invalid input"<< endl;
        } else {
            double k =8.99e9;
            double force=k*(charge*charge)/(distance*distance);
            cout << fixed<<setprecision(3)<< force<< endl;
        }
    }
};
int main() {
    double q, d;
    if (!(cin>>q>>d)) return 0;
    ElectricCharge ec(q, d);
    ec.computeAndDisplay();
    return 0;
}