Only the first 4 people pressing the buzzer are considered, but there still are 6 people who are eligle for consideration. Say the first guys to press the buzzer are in team no 6. Output will be 6xxx and so on...In the worst case it will be 6543, get it?
Well I originally thought the digital outputs will each show 0 or 1 and together they will display the 6 or 4 digit number in binary. log (654321) base 2 = 19.32 = 20 lines and log (6543) base 2 = 12.6 = 13 lines.
But now i came across certain multiplexer circuits/shift register circuits which do the job with fewer digital output lines....
EDIT:I started thinking along the lines of implementing the circuit with whatever components I have in hand at this moment. So after some pondering I realized I could use IC7447s which are BCD to 7 segment display decoders. Since i want each of the 7 segment displays to show only from 1 to 6, ie from 0001 to 0110 BCD. And since the MSB can always be grounded, we require 3 output lines per each 7 segment display. In all 4 displays can be accomodated over 12 digital output lines from 0-11.