using System;

public class Program

{

    public static void Main()

    {

        LopDiem a = new LopDiem();

        LopDiem b = new LopDiem();

        a.Nhap("Nhap diem a:");

        b.Nhap("Nhap diem b:");

        double kq = a.TinhKhoangCach(b);

        Console.WriteLine($"Ket qua la: {kq}");

    }

    public class LopDiem

    {

        public int x;

        public int y;

        public void Nhap(string ghiChu)

        {

            Console.WriteLine(ghiChu);

            Console.WriteLine("Nhap x: ");

            x = int.Parse(Console.ReadLine());

            Console.WriteLine("Nhap y: ");

            y = int.Parse(Console.ReadLine());

        }

        public double TinhKhoangCach(LopDiem b)

        {

            double kq;

            kq = Math.Sqrt((this.x - b.x) * (this.x - b.x) + (this.y - b.y) * (this.y - b.y));

            return kq;

        }

    }

}