I just want to clarify how the rounds will proceed, so correct me if I am wrong.

Preliminaries
Round 1 - 4 contestants -- two contestants win
Round 2 - 4 contestants -- two contestants win
Round 3 - 4 contestants -- two contestants win
Round 4 - 4 contestants -- two contestants win

Semi-finals
Remaining 8 contestants get randomly divided into 2 groups
Round 5 - 4 contestants -- two contestants win
Round 6 - 4 contestants -- two contestants win

Finals
Remaining 4 contestants are placed in 1 group
Round 7 - 4 contestants -- 1 Grand Prize winner, and maybe other consolation prizes.

So the entire contest is 21 days? That is really long.