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

int main() {
	double E, logarithm=0, ai, x;
	int i=2;
	cin >> x >> E;
	if(x!=0){
		ai=(-x*x);
		logarithm=ai;
		while(abs(ai/2)>E){
			ai*=x*x;
			logarithm+=ai/i;
			i++;
		}
	}
	cout <<  logarithm;
	
	return 0;
}