#include<iostream>
#include<math.h>
using namespace std;

const double pi = acos(-1.0);
double a, b;

double give_square (double alpha, double beta)
{
 double gamma = 1.5 * pi - alpha - beta;
 
 double s1 = a * b * sin(alpha) * sin (gamma);
 double s2 = a * a * sin(alpha) * cos(alpha) / 2;
 double s3 = b * b * sin(gamma) * cos(gamma) / 2;

 return s1 + s2 + s3;
}

double give_nice_beta (double alpha)
{
 double l = 0;
 double r = pi;

 for (int i = 0; i < 200; i++)
 {
  double m1 = l + (r - l) / 3;
  double m2 = r - (r - l) / 3;

  double s1 = give_square(alpha, m1);
  double s2 = give_square (alpha, m2);

  if (s1 < s2)
    l = m1;
  else
   r = m2;
 }

 return l;
}

int main()
{
#ifndef ONLINE_JUDGE
 freopen("input.txt", "r", stdin); freopen("output.txt", "w", stdout);
#endif

 cin >> a >> b;

 double l_a = 0, r_a = pi;
 for (int i = 0; i < 200; i++)
 {
  double m1 = l_a + (r_a - l_a) / 3;
  double m2 = r_a - (r_a - l_a) / 3;

  double m1_b = give_nice_beta (m1);
  double m2_b = give_nice_beta (m2);

  double s1 = give_square(m1, m1_b);
  double s2 = give_square(m2, m2_b);

  if (s1 < s2)
   l_a = m1;
  else
   r_a = m2;
 }

 double bb = give_nice_beta (l_a);
 double ans = give_square (l_a, bb);

 printf("%lf", ans);

 return 0;
}