Grid 1

There is a grid with $H$ horizontal rows and $W$ vertical columns. Let $(i, j)$ denote the square at the $i$\-th row from the top and the $j$\-th column from the left. For each $i$ and $j$ ($1 \leq i \leq H$, $1 \leq j \leq W$), Square $(i, j)$ is described by a character $a_{i, j}$. If $a_{i, j}$ is `.`, Square $(i, j)$ is an empty square; if $a_{i, j}$ is `#`, Square $(i, j)$ is a wall square. It is guaranteed that Squares $(1, 1)$ and $(H, W)$ are empty squares. Taro will start from Square $(1, 1)$ and reach $(H, W)$ by repeatedly moving right or down to an adjacent empty square. Find the number of Taro's paths from Square $(1, 1)$ to $(H, W)$. As the answer can be extremely large, find the count modulo $10^9 + 7$. ## Constraints * $H$ and $W$ are integers. * $2 \leq H, W \leq 1000$ * $a_{i, j}$ is `.` or `#`. * Squares $(1, 1)$ and $(H, W)$ are empty squares. ## Input Input is given from Standard Input in the following format: $H$ $W$ $a_{1, 1}$$\ldots$$a_{1, W}$ $:$ $a_{H, 1}$$\ldots$$a_{H, W}$ [samples]