digital communications - HDB3 Waveform: Determining the bit sequence

I was asked to determine the bit sequence of a given HDB3 waveform. I understand that if there are three consecutive 0's then the fourth in that sequence must be a violation pulse. In this example however, I'm confused. Prior to receiving three 0's, the last violation pulse and the last pulse were of positive polarity. After the three 0's there is a negative pulse but how are you supposed to know whether it's just a negative 1 or if it's a negative violation pulse? All I see is three 0's followed by a negative pulse but from what I understand, it could be either a violation pulse or a normal pulse. What is it that I'm not getting?

As seen in the image above, the part that's confusing me is the 10th bit (the first negative pulse). I got that the 6th bit was a violation pulse because it was preceded by three 0's. Any help is much appreciated. By the way, the answer is that it's a negative 1.