def check_exam(arr1, arr2)
  sum = 0
  0.upto(arr1.length - 1) do |i|
    sum += if arr1[i] == arr2[i]
      4
    elsif arr2[i].empty?
      0
    else
      -1
    end
  end
  if sum < 0
    0
  else
    sum
  end
end