#include <iostream.h>
#include <math.h>

double PiSqOver6(double Denom, double Pi){
	if(Denom != 9999)
		return(PiSqOver6(Denom+1,Pi + 1/pow(Denom,2)));
	else
		return(Pi);
}

int main(){
cout<< PiSqOver6(1,0) << endl;
return(0);
}