class S
{
public:
  double s;
  S(double x, double y, double z)
  {
    a = x;
    b = y;
    c = z;
  }
  void TryS();
private:
  double a, b, c;
};
void S::TryS()
{
  try
  {
    if (a + b < c || a + c < b || b + c < a)
    {
      throw(a);
    }
    else
    {
      double p = (a + b + c) / 2;
      s = sqrt(p*(p - a)*(p - b)*(p - c));
      cout << "该三角形的面积为" << s << endl;
    }
  }
  catch (double s)
  {
    cout << "输入的值不能构成三角形" << endl;
  }
}
int main()
{
  S s1(4.3, 2.2, 3.6);
  s1.TryS();
  S s2(1.0, 1.0, 3.0);
  s2.TryS();
  return 0;
}