Holocaust..did it happen?

If i was talking to somebody who believed  that holocaust didn't exist, i would say to them it did exist. Through all the tracking and systems of tracking how many people were involved in this genocide, it would be impossible to believe that it really didn't happen. The conspiracy would be too hard to follow and countries and survivors wouldn't just make up unrealistic stories of what had happened during the holocaust. It was a major part of world history and there is no way to go around it.