Economic Phonebook

Due to the large number of complaints, the telephone company of St. Petersburg is being forced to invest heavily in improving its services. To do this, the company decided to reduce the budget of some sectors to increase other more essential. One of the sectors that will have its budget reduced is the printing of phone books.

With a reduced budget, the sector of printing phonebooks can not buy enough toner to print the complete lists. As telephone numbers are printed vertically aligned, it was suggested the following solution: from the second phone number printed, the initial digits of the next number to be printed that match the above number are omitted, leaving only one space white. For example, for the numbers 535456, 535488, 536566 and 835456 would be printed is as follows:

5 3 5 4 5 6
        8 8
    6 5 6 6
8 3 5 4 5 6

Note that this impression has saved the impression 6 characters. The telephone company also wondered not print the repeated suffixes, but in tests saw that the answer was not good for the user and therefore decided to make only the elimination prefixes. To determine whether the economy will be sufficient, the printing industry wants to know the maximum number of characters that can be omitted. However, as in any big city, there are several phone numbers and they do not want to spend man-hours to manually calculate this value. So it's up to you, new employee of the company, automate the economy made ​​by toner, the number of characters.