Standardized Test#580
To simplify standardized tests in literature, it was decided to include only questions with «yes» or «no» answers. The answer sheet is a grid of rows and columns, where each cell corresponds to a question. The student must mark diagonally, exactly once, those cells that they believe correspond to «no» answers (they may use either diagonal direction for the mark). To prevent scanning errors, no two diagonals must "merge," meaning no two may share an endpoint.
Test authors need to determine the maximum number of «no»-answer questions that can be included in a variant so that the answer sheet with correct answers can be correctly recognized by a computer.
You will be given two natural numbers — the number of rows and the number of columns . The number of questions in a variant does not exceed , i.e., 1 \leq N \cdot M \leq 100.
Print one number on the first line — the maximum number of «no»-answer questions that can be included in the variant. On the next lines, print characters each — an example of such an answer sheet with correct answers that can be recognized by the computer. No two diagonals should share endpoints. Use the following notations: . (dot) — an empty cell, corresponding to a «yes» answer; / or \ — cells marked diagonally from right to left or left to right, corresponding to «no» answers. If there are multiple valid answer sheets, output any one of them.
Example 1