using System;

public class Program

{

    public class DIEM

    {

        public int X; 

        public int Y;

        public void Nhap(string ghiChu)

        {

            Console.WriteLine(ghiChu);

            Console.WriteLine("Nhap X");

            this.X = int.Parse(Console.ReadLine());

            Console.WriteLine("Nhap Y");

            this.Y = int.Parse(Console.ReadLine());

        }

        public double TinhKhoanCach(DIEM B)

        {

            return Math.Sqrt(Math.Pow(this.X - B.X,2) + Math.Pow(this.Y - B.Y,2));

        }

    }

    public class TAMGIAC

    {

        public DIEM A;

        public DIEM B;

        public DIEM C;

        public TAMGIAC()

        {

            this.A = new DIEM();

            this.B = new DIEM();

            this.C = new DIEM();

        }

        public void Nhap(string ghiChu)

        {

            Console.WriteLine(ghiChu);

            this.A.Nhap("Nhap diem A");

            this.B.Nhap("Nhap diem B");

            this.C.Nhap("Nhap diem C");

        }

        public double TinhChuVi()

        {

            double a, b, c;

            a= B.TinhKhoanCach(C);

            b= A.TinhKhoanCach(C);

            c= B.TinhKhoanCach(A);

            return a+b+c;

        }

    }

    public static void Main()

    {

        TAMGIAC t = new TAMGIAC();

        t.Nhap("Nhap tam giac");

        var kq = t.TinhChuVi();

        Console.WriteLine(kq);

    }

}