Well...I got close within 5 mins..it was the last few I missed, till I knew the answer, then it was apparent...look closely...at the number of people, what they did and the other angle!
EDIT: Kohi, where are you getting 22 from man?!!!!
I have PM'd Robbo, to see what he thinks, if he turns up...coz he used to be a Maths Proffesor (or so I believe)...