We all know, Argentina and Brazil supporters cannot stand each other. An organization decided to arrange a seminar about the importance of peace between football supporters. They invited MMM Brazil supporters and NNN Argentina supporters. They sat in a row. But if a Brazil and an Argentina supporter sat together, they fought. Even these supporters were so energetic that if one fought with his opponent on the left side and there was an opponent on the right side, he again fought. Each day the organization arranged sit differently from any previous arrangement hoping that there would be no fight. They stopped this seminar when they ran out of new permutations and realized there would never be peace between Argentina and Brazil supporters. Your task is to find out on average how many fights were there daily.
This is a companion discussion topic for the original entry at https://toph.co/p/fight-fight-fight