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

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