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

class ElectricCharge{
    private:
    double charge,distance;
    
    public:
    ElectricCharge(double c,double d){
        if(c<=0 || d<=0){
            cout<<"Invalid input";
        }else{
            double k=8.99e9;
            double force=k*c*c/(d*d);
            cout<<fixed<<setprecision(3)<< force;
        }
    }
};
int main() {
    double charge distance;
    cin>>charge>>distance;
    
    ElectricCharge obj(charge,distance);
    
    return 0;
}