using System;
public class Program
{
public static void Main()
int mark;
char grade;
Console.WriteLine("Please insert your grade");
mark=Convert.ToInt32(Console.ReadLine());
if(mark>=75 && mark<=100)
Console.WriteLine('A');
else if(mark>=50 && mark<=74)
Console.WriteLine('B');
else if(mark>=0 && mark>=49)
Console.WriteLine('C');
}