A novel method and system for storing high purity hydrogen into a salt cavern is provided. The social network information can include user profile information and indicate existing social relationships between the users in the social network. As a result of the check, if data necessary to execute the program does not exist in the memory area, the memory area is released. Accordingly, if an automatic density adjustment based upon prescanning has been designated, prescanning is carried out and then a histogram is obtained for each of the components R, G and B and the background levels are calculated for color scanning and monochrome scanning. A removable base engages with the bottom end of the bird feed container.