using System;

public class Program

{

    public static void Main()

    {

        Console.WriteLine("กรุณากรอกคะแนนกลางภาค :");

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

        Console.WriteLine("กรุณากรอกคะแนนปลายภาค :");

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

        int total = mt + mm;

        if(total < 50){

        Console.WriteLine("your poin {0}Your grade is {1} :",total,"F");

        }else if(total < 55){

        Console.WriteLine("your poin {0} Your grade is {1} :",total,"D");   

        }else if(total < 60){   

        Console.WriteLine("your poin {0} Your grade is {1} :",total,"D+");

        }else if(total < 65){   

        Console.WriteLine("your poin {0} Your grade is {1} :",total,"C");

        }else if(total < 70){   

        Console.WriteLine("your poin {0} Your grade is {1} :",total,"C+");

        }else if(total < 75){

        Console.WriteLine("your poin {0} Your grade is {1} :",total,"B");

        }else if(total < 80){

        Console.WriteLine("your poin {0} Your grade is {1} :",total,"B+");

        }else{

        Console.WriteLine("your poin {0} Your grade is {1} :",total,"A");

            }   

    }

}   

​