#include <iostream>

#include <algorithm>

#include <cstdio>

#include <cmath>

using namespace std;

#define EPS 1e-9

//1874 to calculate the max area

//divide quardnage into two areas

//helper function to cal the area

double cal_area(double a, double b, double c)

{

        //check if theree exists triangle, otherwise, it will rturn nan, which is not comparable

        if(c + a <= b || c + b <=a || a+b <=c) return -;

        double s = (a+b+c)/2.0;

        double s1 = c*c/;

        double s2 = sqrt(s*(s-a)*(s-b)*(s-c));

        return s1+s2;

}

int main(){

  //freopen("input.txt","r",stdin);

  double a = , b = ;

  cin >> a; cin >> b;

  double c = ;

  //uble s1 = 0, s2 = 0;

  double max = ;

  //the range of c is [0 a+b]

  double l = , r = a+b;

  double m,mm;

  double mv, mmv;

  while(l + EPS < r)

  {

        m = (r-l)/ + l;

        mm = (r-m)/ + m;

        mv = cal_area(a,b,m);

        //printf("%f\n", mv);

        mmv = cal_area(a, b, mm);

        //find first construct area

        if(mv <= mmv) l = m;// edge case if mv == mmv(move to bigger one tot get bigger c)

        else r = mm;

  }

  printf("%.7f\n",mv, mmv, mv > mmv ? mv : mmv);

  return ;

}