Farmer John has left some old mirrors sitting outside his house, and his cows have stolen them!

The cows have set up the mirrors in a rectangular field measuring N by M squares (1 <= N, M <= 1,000). In each square, they have placed a double sided mirror between two of its opposite corners. These two configurations are represented by the '/' character (a mirror connecting the lower-left corner to the upper-right corner) and the '\' character (a mirror connecting the upper-left corner to the lower-right corner).

One evening, Bessie brings a laser pointer out to the mirror field. Standing outside the field, she shines the beam of light either horizontally or vertically along either a row or column of the field, causing it to bounce off some number of mirrors. Since the mirrors are all diagonally oriented, a horizontal beam that reflects off a mirror will end up traveling vertically, and vice versa. Bessie wonders what is the maximum number of mirrors on which her beam of light can be reflected. Given the layout of the mirror field, please help Bessie compute this number.

Line 1: The integers N and M, separated by a space.

Lines 2..1+N: Each line will contain M '/' or '\' characters, describing a row of the mirror field.

A single integer indicating the maximum number of times a horizontal or vertical beam originating outside the mirror field could be reflected. Output -1 if it could be reflected indefinitely.

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