B'Madoka as a child was an extremely capricious girl, and one of her favorite pranks was drawing on her wall. According to Madoka 's memories, the wall was a table of n rows and m columns, consisting only of zeroes and ones. The coordinate of the cell in the i -th row and the j -th column ( 1 <= i <= n , 1 <= j <= m ) is (i, j) . One day she saw a picture "Mahou Shoujo Madoka Magica" and decided to draw it on her wall. Initially, the Madoka 's table is a table of size n x m filled with zeroes. Then she applies the following operation any number of times: Madoka selects any rectangular subtable of the table and paints it in a chess coloring (the upper left corner of the subtable always has the color 0 ). Note that some cells may be colored several times. In this case, the final color of the cell is equal to the color obtained during the last repainting. For better understanding of the statement, we recommend you to read the explanation of the first test. Help Madoka and find some sequence of no more than n cdot m operations that allows you to obtain the picture she wants, or determine that this is impossible. Each test contains multiple test cases. The first line contains a single integer t ( 1 <= t <= 10 ) -- the number of test cases. Description of the test cases follows. The first line of each test case contains two integers n and m ( 1 <= q n, m <= q 100 ) -- the size of the table. Each of the following n lines contains a string of length m consisting only of 1 and 0 -- description of the picture that Madoka wants to obtain. If it is impossible to obtain the given picture, print -1 . Otherwise, print in the first line a single integer q ( 0 <= q q <= q n cdot m ) -- the number of operations you need to obtain the picture. Note that you do not need to minimize the number of operations. Then for each operation (in the orde'...