Jugadu likes reading sports and science magazines. He went to purchase it from a shop, but he couldn't find the magazines as the shelves were empty. He went to ask the shopkeeper, the shopkeeper told him that he has more copies of the magazines but was unaware that the magazines were not on the shelf. The shopkeeper further told him that earlier too he had lost so many customers due to empty shelf. He wants something which can indicate the empty shelf. Can you help Jugaadu?