Consider a system with a total of 4 page frames and an application accessing memory according to this reference string of virtual page numbers (VPNs): 4 1 2 0 3 5. Complete the mapping table for a process at different times (t₀: initial mapping, t₁: mapping after accessing VPN 4, etc.) if clock page replacement is used. Assume that the circular buffer of the clock is in ascending order (i.e., frame 0, 1, 2, 3), that the clock hand at t₀ is positioned at frame 0 and that the reference bit for page 7 (in frame 2) is set, and cleared for the other pages.

Frame	VPN(t0)	VPN(t1)	VPN(t2)	VPN(t3)	VPN(t4)	VPN(t5)	VPN(t6)
0	3	?	?	?	?	?	?
1	1	?	?	?	?	?	?
2	7	?	?	?	?	?	?
3	6	?	?	?	?	?	?

Fill in the question marks.