Chessboard

Write a program that prints a chessboard with N rows and M columns under these rules.

• The top left cell is an asterisk (*).
• Every cell that touches a cell holding an asterisk, above, below, to the left or to the right, holds a dot (.).
• Every cell that touches a cell holding a dot holds an asterisk.

Printing a chessboard with 8 rows and 8 columns under these rules gives:

*.*.*.*.
.*.*.*.*
*.*.*.*.
.*.*.*.*
*.*.*.*.
.*.*.*.*
*.*.*.*.
.*.*.*.*

One line with two integers N and M separated by a space. N is the number of rows and M is the number of columns. Both N and M are between 1 and 10.

Print N lines, each holding M characters, that form the chessboard.