Submit solution

Points:
10 (partial)

Time limit:
5.0s

Memory limit:
1G

Problem type

Allowed languages

Ada, Assembly, Awk, Brain****, C, C#, C++, COBOL, ~~CommonLisp~~, D, Dart, F#, Forth, Fortran, Go, ~~Groovy~~, Haskell, Intercal, Java, JS, Kotlin, Lisp, Lua, ~~Nim~~, ~~ObjC~~, OCaml, ~~Octave~~, Pascal, Perl, PHP, Pike, Prolog, Python, Racket, Ruby, Rust, Scala, Scheme, Sed, Swift, TCL, Text, Turing, VB, Zig

An -by- grid is *good* if every square is colored either red or blue, and if the square in row , column
is blue, then every square in row , column that satisfies and must also be colored blue.

You are given a grid that is partially colored in. Count the number of ways to color the remaining squares of the grid such that the grid is good.

#### Constraints

At least one square in the grid will be `.`

.

#### Input Specification

The first line contains two space-separated integers and .

Each of the next lines contains characters representing the grid. Each character is either `R`

to represent a red square, `B`

to represent a blue square, or `.`

to indicate a square that has not been colored.

#### Output Specification

Print, on a single line, the number of distinct colorings possible.

#### Sample Input

```
3 2
..
B.
.R
```

#### Sample Output

`6`

#### Sample Input

```
7 6
......
.....B
.B..R.
......
...B..
.R....
...R..
```

#### Sample Output

`3`

#### Sample Input

```
2 2
R.
.B
```

#### Sample Output

`0`

## Comments