Write an application named EnterUppercaseLetters that asks the user to type an uppercase letter from the keyboard. If the character entered is an uppercase letter, display OK; if it is not an...

Write an application named EnterUppercaseLetters that asks the user to type an uppercase letter from the keyboard. If the character entered is an uppercase letter, display OK; if it is not an uppercase letter, display an error message. The program continues until the user types an exclamation point. The program should be in C#