```
def findBlackPixel(self, picture, N):
res = 0
C = list(zip(*picture))
for col in C:
if col.count('B')==N:
BIndex = [i for i, x in enumerate(col) if x == "B"]
CI=0
for i in range(N):
if picture[BIndex[i]].count('B') == N:
CI += 1
Pattern = picture[BIndex[i]]
break
for j in range(i+1,N):
if Pattern != picture[BIndex[j]]:
break
CI+=1
if CI == N:
res +=N
return res
```