Student Mark Categorizer

A teacher needs a program to categorize student test marks. The program will continuously read integer marks until a value of -1 is entered.

The marks should be sorted into three categories:

• Higher: 80 or greater
• Middle: 50 to 79 (inclusive)
• Lower: less than 50

At the end, output the total counts for each category.

Input: A sequence of integers ending with -1. Output: Three lines formatted as "Higher: X", "Middle: Y", and "Lower: Z".

Example:

Input:  85 50 49 90 12 -1
Output: Higher: 2
        Middle: 1
        Lower: 2