```
class Solution {
public:
int findLonelyPixel(vector<vector<char>>& picture) {
if(picture.empty()) return 0;
int rows = picture.size(), cols = picture[0].size();
int count = 0;
for(int i = 0; i < rows; i++){
for(int j = 0; j < cols; j++){
if(picture[i][j] == 'B'){
int res = helper(picture, i, j);
count += res;
}
}
}
return count;
}
private:
int helper(vector<vector<char>>& picture, int i, int j){
int rows = picture.size(), cols = picture[0].size();
for(int k = 0; k < rows; k++){
if(k == i) continue;
if(picture[k][j] == 'B') return 0;
}
for(int k = 0; k < cols; k++){
if(k == j) continue;
if(picture[i][k] == 'B') return 0;
}
return 1;
}
};
```