# LRU code

# defining the table size

table_size = 3

reference_string = [0, 1, 2, 3, 0, 1, 4, 0, 1, 2, 3, 4]

# the list which stores the current pages in memory

# and where page replacement is executed.

pages = []

# page faults

faults = 0

# iterating through the ref string

for page in reference_string:

	# check if page already exists in the list, 

	# if yes, we just remove the page and append it

	# to the end of the list (last index).

	if page in pages:

		# removing

		pages.remove(page)

		# appending

		pages.append(page)

	# if page is not there

	else:

		# we first check length of page list. 

		# if still spots left in the list, we first fill it

		if(len(pages) < table_size):

			pages.append(page)

		else:

			# if the page list is filled. We remove the 

			# first page. 

			pages.remove(pages[0])

			# and then we append page to the end of list. 

			pages.append(page)

		# Increment 1 in Page faults

		faults +=1

print("total page faults = ", faults)