-- Homework 16, problem 3: Grade letter.
--
-- Prompt for a score 0-100. Print:
--   Grade: A   if score >= 90
--   Grade: B   if score >= 80
--   Grade: C   if score >= 70
--   Grade: D   if score >= 60
--   Grade: F   otherwise
--
-- Run with: lua exercises/16/homework/03-grade-letter.lua

-- Your code goes here: