I just noticed that there are 6 groups in the current European Championships, which means that - if the top two from each group were to go through - there would only be 12 teams into the last 16, which is 4 short.
However, if the top 3 from each group go through, we get 18 teams going to the round of 16, which is 2 too many.
There would have to be just 4 groups where 3 teams go through and 2 groups where the top 2 go through to make 16 teams in the round of 16.
How is it working?
Are there 4 groups where 3 teams go through? If so, how do they decide which groups?