#include <iostream>
#include <cstdio>
#include <algorithm>
#include <cfloat>

using namespace std;

int main() {
	int nlamp;
	double A;

	while ( cin >> nlamp >> A ) {
		double minB = A + (nlamp - 1) * (nlamp - 2);
		for ( int n = 1; n <= nlamp - 2; n++ ) {
			const int m = nlamp - 1 - n;

			const double H = max(0.0, A - n*(n + 1));
			const double h = ((A - H) - n*(n - 1)) / n;

			if ( h < 0 || h > 2 ) continue;
			const double g = 2 - h;

			const double B = H + m*g + m*(m - 1);
			if ( B < minB ) minB = B;
		}

		// n = nlamp - 1 の場合は落ちて終わりの場合がある.
		const int n = nlamp - 1;
		const double h = A - n*(n - 1);
		if ( h >= 0 ) minB = 0.0;

		printf("%.2lf\n", minB);
	}

	return 0;
}