The input file contains one or more board descriptions, followed by a line containing the number $0$

that signals the end of the file. Each board description begins with a line containing a positive integer

n that is the size of the board; n will be at most $4.$ The next n lines each describe one row of the board,

with a $.$ indicating an open space and an uppercase $$X$$ indicating a wall. There are no spaces in the

input file.

Output

For each test case, output one line containing the maximum number of rooks that can be placed on the

board in a legal configuration.