Input student score and outputs grade results with message.

exam_result

#output grade results dependent on student score

puts "Enter the students score: "
score = gets.to_i
while score > 100
	puts "You must enter a number less then or equal to 100 "
	puts "Enter the students score: "
	score = gets.to_i
end
while score == 100
	puts "PERFECT SCORE! FANTASTIC! A score of #{score} gives you a perfect A"
	exit
end
while score >= 90 and score <= 99
	puts "CONGRATULATIONS! A score of #{score} gives you an A"
	exit
end
while score >= 80 and score <= 89
	puts "Very good! A score of #{score} gives you a B"
	exit
end
while score >= 70 and score <= 79
	puts "You can do better. A score of #{score} gives you a C"
	exit
end
while score >= 60 and score <= 69
	puts "Warning! Be careful. A score of #{score} gives you a D"
	exit
end
while score <= 59
	puts "FAILURE! You have failed your exam. A score of #{score} gives you an F"
	exit
end