package main

import "fmt"
import "math"

type Rectangle struct {
	x1, y1, x2, y2 float64
}

func (r *Rectangle) length() float64 {
	return distance(r.x1, r.y1, r.x1, r.y2)
}
func (r *Rectangle) width() float64 {
	return distance(r.x1, r.y1, r.x2, r.y1)
}

func (r *Rectangle) area() float64 {
	return r.length() * r.width()
}
func (r *Rectangle) perimeter() float64 {
	return 2*r.length() + 2*r.width()
}

type Circle struct {
	x float64
	y float64
	r float64
}

func (c *Circle) area() float64 {
	return math.Pi * c.r * c.r
}
func (c *Circle) perimeter() float64 {
	return 2 * math.Pi * c.r
}

type Shape interface {
	area() float64
	perimeter() float64
}

type MultiShape struct {
	shapes []Shape
}

func (m *MultiShape) area() float64 {
	var area float64
	for _, s := range m.shapes {
		area += s.area()
	}
	return area
}
func (m *MultiShape) perimeter() float64 {
	var perimeter float64
	for _, s := range m.shapes {
		perimeter += s.perimeter()
	}
	return perimeter
}

func distance(x1, y1, x2, y2 float64) float64 {
	a := x2 - x1
	b := y2 - y1
	return math.Sqrt(a*a + b*b)
}

func main() {
	c := &Circle{x: 1, y: 1, r: 4}
	r := &Rectangle{x2: 4, y2: 10}
	ms := MultiShape{[]Shape{c, r}}
	fmt.Println("Area", ms.area())
	fmt.Println("Perimeter", ms.perimeter())
}