using System;

public class Program

{

    public static void Main(string[] args)

    {

            Double x1=0;

            Double x2=0;

            Double y1=0;

            Double y2=0;

            Double rasstoyanie;

            Console.Write("x1=");

            x1 = Convert.ToDouble(Console.ReadLine());

            Console.Write("x2=");

            x2 = Convert.ToDouble(Console.ReadLine());

            Console.Write("y1=");

            y1 = Convert.ToDouble(Console.ReadLine());

            Console.Write("y2=");

            y2 = Convert.ToDouble(Console.ReadLine());

            rasstoyanie = Math.Sqrt(Math.Pow(x2-x1,2)+Math.Pow(y2-y1,2));

            Console.WriteLine("Расстояние:" + rasstoyanie);

            Console.ReadLine();

    }                             

​

}