-- Homework 16, problem 3 -- solution.

io.write("Score (0-100): ")
local score = tonumber(io.read())

if score >= 90 then
    print("Grade: A")
elseif score >= 80 then
    print("Grade: B")
elseif score >= 70 then
    print("Grade: C")
elseif score >= 60 then
    print("Grade: D")
else
    print("Grade: F")
end