# 0531. Lonely Pixel I

<https://leetcode.com/problems/lonely-pixel-i>

## Description

Given an `m x n` `picture` consisting of black `'B'` and white `'W'` pixels, return *the number of **black** lonely pixels*.

A black lonely pixel is a character `'B'` that located at a specific position where the same row and same column don't have **any other** black pixels.

**Example 1:**

![](https://assets.leetcode.com/uploads/2020/11/11/pixel1.jpg)

```
**Input:** picture = [["W","W","B"],["W","B","W"],["B","W","W"]]
**Output:** 3
**Explanation:** All the three 'B's are black lonely pixels.
```

**Example 2:**

![](https://assets.leetcode.com/uploads/2020/11/11/pixel2.jpg)

```
**Input:** picture = [["B","B","B"],["B","B","W"],["B","B","B"]]
**Output:** 0
```

**Constraints:**

* `m == picture.length`
* `n == picture[i].length`
* `1 <= m, n <= 500`
* `picture[i][j]` is `'W'` or `'B'`.

## ac

```java
```