#include <iostream>
#include<iomanip>

class Electriccharge{
    double q,d;
    public:
    Electriccharge(double c,double s):q(c),d(s){}
    void show(){
    if(q<=0||d<=0)std::cout<<"Invalid input";
    else std::cout<,std::fixed<,std::setprecision(3)<,8.99e9*q/(d*d);
}
};
int main(){
    double q,d;
    if(std::cin>>q>>d)Electriccharge(q,d).show();
    return 0;
}