public static void Main()
Console.WriteLine("How Many Credit Hours Have You Earned?");
string input = Console.ReadLine();
int creditsEarned = int.Parse(input);
Console.Write("Freshman");
(30 <= creditsEarned && creditsEarned < 60)
Console.WriteLine("Sophomore");
(60 <= creditsEarned && creditsEarned < 90)
Console.WriteLine("Junior");
(90 <= creditsEarned && creditsEarned <= 999)
Console.WriteLine("Senior");