interface InterfaceEx1
{
    double area ();

}
interface InterfaceEx2
{
    double perimeter();
}

class Figure : InterfaceEx1, InterfaceEx2{
   /* dummy class */
  double area () { return 0.0;}
  double perimeter (){ return 0.0;}
}


class Rectangle : Figure
{
  private import math2;
 private:
  double side_1;
  double side_2;
  
 export
   {
     double get_side_1() {return side_1;}
     double get_side_2() {return side_2;}

     this (){
       side_1 = 1.0;
       side_2 = 1.0;
     }

     this (double s1, double s2){
       side_1 = s1;
       side_2 = s2;
     }
     
     double area ()
       out (result){
       assert(feq(result, (get_side_1() * get_side_2())));
     }
     body { 
       return (get_side_1()  * get_side_2());
     }
     
     double perimeter (){
       return (2 * (get_side_1() + get_side_2()));
     }
   }
}


class Circle: Figure
{
  import math;
 private:
  double radius;
 public
   {
     this (){
       radius = 1.0;
     }
     
     this (double init_val){
       radius = init_val;
     }

     double get_radius (){return radius;}
     
     double area (){
       return (PI * radius * radius);
     }

     double perimeter (){
       return (PI * 2 * radius);
     }
   }
}

class Triangle : Figure
{
  private import math2;
  private import math;
 private:
  double epsilon = 0.001;
  double side_a, side_b, side_c;

      
  public {
    this (){
      side_a = side_b = side_c = 1.0;
    }

    this (double sa, double sb, double ag){
      /* Given side a, side b and the enclosing angle */
      double angle_gamma = deg2rad(ag);
      side_a = sa; side_b = sb; 
      side_c = sqrt((sa * sa) + (sb * sb) - 2 * side_a * side_b * cos(angle_gamma));
    }

    double area (){
      /* Heron'sche Formel */
      double s = ((side_a + side_b + side_c) / 2);
      return (sqrt(s * (s - side_a) * (s - side_b) * (s - side_c)));
    }

    double perimeter (){
      return side_a + side_b + side_c;
    }
    
    
  }
}    
 
unittest {
  assert(10.001 ==  10.00);
  assert(feq (rad2deg(deg2rad (90.0)), 90.0));
}   
      
  
import c.stdio; // for  sscanf
int main (char [] [] args){

  char [] v1;
  char [] v2;
  double dv1, dv2;

  sscanf(args[1], "%lf", &dv1);
  sscanf(args[2], "%lf", &dv2);
  Figure fig  = new Rectangle(dv1, dv2);
  
  printf("Rectangle: area = %.2lf, perimeter = %.2lf\n",
         fig.area(), fig.perimeter());
  

  fig  = new Circle(10.0);
  printf("Circle area = %.2lf, perimeter = %.2lf\n", 
         fig.area(), fig.perimeter());

  fig = new Triangle();
  printf("Triangle  area = %.2lf, perimeter = %.2lf\n", 
         fig.area(), fig.perimeter());
  return 0;
}