Exercise 1: Even or odd
Prompt the user to enter an integer. Determine whether a given number is even or odd
Exercise 2: Grading System
Write a program that takes a student's score as input and prints their corresponding grade based on the following grading scale:
90 and above: A
80 - 89: B
70 - 79: C
60 - 69: D
Below 60: F
Exercise 3: Calculator Program
Write a simple calculator program that takes two numbers and an operator (+, -, *, /) as input and performs the corresponding arithmetic operation.
