operating system ?

n pure on-demand paging, a page replacement policy is used to manage system resources. Suppose that a newly created process has 6-page frames allocated to it, and then generates the page references indicated below. 1,2,3,4,2,1,5,6,2,1,2,3,7,6,3,2,1,2,3,6 How many page faults would occur with FIFO page replacement