#include 
#include 
#include 

typedef enum {
    LINE, CIRCLE, RECTANGLE
} ShapeKind ;

typedef struct {
    double x, y;
} Point;

typedef struct {
    Point p1, p2;
} Line;

typedef struct {
    Point centre;
    int radius;
} Circle;

typedef struct {
    Point top_left;
    double width, height;
} Rectangle;

typedef struct {
    ShapeKind kind;
    int color;
    union {
        Line line;
        Circle circle;
        Rectangle rectangle;
    } u;
} Shape;

typedef struct {
    Shape shapes[MAX_SHAPE];
	int size;
} Canvas;

Point point(double x, double y)
{
    Point p = {x, y};
    return p;
}

Shape line(Point p1, Point p2, int color)
{
    Line l = {p1, p2};
    Shape s = {LINE, color};
    s.u.line = l;
    return s;
}

Shape circle(Point centre, double radius, int color)
{
    Circle c = {centre, radius};
    Shape s = {CIRCLE, color};
    s.u.circle = c;
    return s;
}

Shape rectangle(Point top_left, double width, double height, int color)
{
    Rectangle r = {top_left, width, height};
    Shape s = {RECTANGLE, color};
    s.u.rectangle = r;
    return s;
}

double area(Shape s)
{
    switch( s.kind ) {
        case LINE:
            return 0;
        case CIRCLE:
            return M_PI * s.u.circle.radius *  s.u.circle.radius;
        case RECTANGLE:
            return s.u.rectangle.width * s.u.rectangle.height;
        default:
            fprintf(stderr, "ERRO\n"); exit(1);
    }
}

int main(void)
{
    Shape c = circle(point(0,0), 1, 99);
    printf("%f\n", area(c));
    return 0;
}