SCU wants 3 of its branches to be able to print, scan, distribute, and OCR black and white typed documents among themselves. The network is Windows 2003 Active Directory domain with Windows XP clients. The LANs are running at 100 Mbps and connected via 3Mbps DSL. The 3 branches need to scan and print 500-1000 sheets daily. What is the minimum resolution for black and white scanned images used in OCR?