#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()
{
    doubleq,d;
    if (cin>>q>>d)ElectricCharge(q,d).show();
    return 0;
}