using System;

​

class Program

{

    private struct Vertex

    {

        public int x;

        public int y;

    }

​

    static void Main(string[] args)

    {

        Vertex aVertex = inputVertex("a");

        Vertex bVertex = inputVertex("b");

        Vertex cVertex = inputVertex("c");

​

        double perimeter = getDistanceValue(aVertex, bVertex) + 

            getDistanceValue(aVertex, cVertex) + 

            getDistanceValue(bVertex, cVertex);

​

        Console.WriteLine($"Perimeter = {perimeter}");

​

        Console.ReadLine();

    }

​

    private static Vertex inputVertex(String vertexName)

    {

        Vertex vertex;

        Console.WriteLine(vertexName);

        Console.WriteLine($"Input x");

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

        Console.WriteLine($"Input y");

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

        return vertex;

    }

​

    private static double getDistanceValue(Vertex aVertex, Vertex bVertex)

    {

        return Math.Sqrt(Math.Pow(aVertex.x - bVertex.x, 2) + Math.Pow(aVertex.y - bVertex.y, 2));

    }

}