**Time limit:**1.00 s**Memory limit:**512 MB

Your task is to calculate the number of paths from the upper-left square to the lower-right square where you only can move right or down.

**Input**

The first input line has an integer $n$: the size of the grid.

After this, there are $n$ lines that describe the grid. Each line has $n$ characters:

`.`

denotes an empty cell, and `*`

denotes a trap.**Output**

Print the number of paths modulo $10^9+7$.

**Constraints**

- $1 \le n \le 1000$

**Example**

Input:

`4`

....

.*..

...*

*...

Output:

`3`