Bro, it doesn't work like this. Let me teach and educate you why:
Ok, so you say that we split the coins into 3 groups: 5, 5 and 2
Then you take the one of the group of 5 coins and:
1. 2 - 2... and you put 1 coin aside.
if they are balanced the cf coin will be in other 8 coins
2. You do the same with the second group of 5 coins - if they are balanced the cf coin will be in the remaining 4 coins( 2 you put aside + third group of 2 coins)
3. now how do you find the cf coin in these 4 coins?
Tell me, homeboy.