B'You have a large rectangular board which is divided into n x m cells (the board has n rows and m columns). Each cell is either white or black. You paint each white cell either red or blue. Obviously, the number of different ways to paint them is 2^w , where w is the number of white cells. After painting the white cells of the board, you want to place the maximum number of dominoes on it, according to the following rules: Let the value of the board be the maximum number of dominoes you can place. Calculate the sum of values of the board over all 2^w possible ways to paint it. Since it can be huge, print it modulo 998 ,244 ,353 . The first line contains two integers n and m ( 1 <= n, m <= 3 cdot 10^5 ; nm <= 3 cdot 10^5 ) -- the number of rows and columns, respectively. Then n lines follow, each line contains a string of m characters. The j -th character in the i -th string is * if the j -th cell in the i -th row is black; otherwise, that character is o. Print one integer -- the sum of values of the board over all 2^w possible ways to paint it, taken modulo 998 ,244 ,353 . '...