why doesn't ruby calculator work?(hepl pls)

Question

Code:
print "Введити цифру: "
input_number = gets.to_i
print "Введите цифру "
input_nubmer_two = gets.to_i
print "Введите знак: "
input_znak = gets
case input_znak
when '+'
puts "#{input_number+input_nubmer_two}"
when '-'
puts "#{input_number-input_number_two}"
when '/'
puts "#{input_number/input_nubmer_two}"
when '*'
puts "#{input_number*input_nubmer_two}"
end