using System;

public class Polygon {

  private Point[] corners;
  
  public Polygon(params Point[] corners){
    this.corners = new Point[corners.Length];

    // Copy corners into instance variable:
    for(int i = 0; i < corners.Length; i++)
      this.corners[i] = new Point(corners[i]);
  }

  private Line[] Edges(){
    Line[] res = new Line[corners.Length];
    int Lgt = corners.Length;
    for (int i = 0; i < Lgt - 1; i++)
       res[i] = new Line(corners[i], corners[i+1]);
    res[Lgt-1] = new Line(corners[Lgt-1], corners[0]);
    return res;
  }

  public virtual double Circumference(){
    double res = 0;
    foreach(Line ln in this.Edges())
      res += ln.Length();
    return res; 
  }

  public virtual int Rank{
    get {
      return corners.Length;}
  }

}

internal class Line{

 private Point p1, p2;
 
 public Line(Point p1, Point p2){
   this.p1 = new Point(p1);
   this.p2 = new Point(p2);
 }

 public double Length(){
   return Math.Sqrt(
            Square(p1.X - p2.X) + 
            Square(p1.Y - p2.Y));
 }

 private static double Square(double a){
   return a * a;
 }
}