Exercise 3: Sum of Even Numbers

Write a Python function to calculate the sum of all even numbers from 1 to a given positive integer (inclusive). The function should take an integer `n` as input and return the sum of all even numbers between 1 and `n`.

1. Function: `sum_even_numbers(n)`

   – This function takes a positive integer `n` as input and returns the sum of all even numbers from 1 to `n`.

In the main part of the program, ask the user to input a positive integer and call the `sum_even_numbers()` function to compute and display the sum of even numbers.