Condition to check if if statement fails just once?

How can I check that my if statement as below fails just once? Is there a way to check how many times it fails?

Right now I am using any but that means it could be failing more than once?

for j in range (0,n):
     for k in range (0,n):
            while True:
                 if any(X[i][j]!=X[k])
....