Codeforces Round #363 (Div. 1) A.py

n = int(input())

raw = input().split(" ")

decisions = []

# decide first move
for i in range(1):
	# gym no, contest no
	if raw[i] == "0":
		decisions.append("Rest")
	# gym no, contest yes
	elif raw[i] == "1":
		decisions.append("Contest")
	# gym yes, contest no
	elif raw[i] == "2":
		decisions.append("Gym")
	# gym yes, contest yes
	elif raw[i] == "3":
		index = i
		while True:
			# still does not meet any no in the end
			# example: yes yes, yes yes, yes yes, yes yes
			if index == n - 1:
				# choose any
				decisions.append("Gym")
				break

			# gym no, contest no
			if raw[index + 1] == "0":
				# choose any
				decisions.append("Gym")
				break
			# gym no, contest yes
			elif raw[index + 1] == "1":
				decisions.append("Gym")
				break
			# gym yes, contest no
			elif raw[index + 1] == "2":
				decisions.append("Contest")
				break
			# gym yes, contest yes
			elif raw[index + 1] == "3":
				index += 1

for i in range(1, n):
	# gym no, contest no
	if raw[i] == "0":
		decisions.append("Rest")
	# gym no, contest yes
	elif raw[i] == "1":
		if decisions[i - 1] == "Rest":
			decisions.append("Contest")
		elif decisions[i - 1] == "Gym":
			decisions.append("Contest")
		elif decisions[i - 1] == "Contest":
			decisions.append("Rest")
	# gym yes, contest no
	elif raw[i] == "2":
		if decisions[i - 1] == "Rest":
			decisions.append("Gym")
		elif decisions[i - 1] == "Gym":
			decisions.append("Rest")
		elif decisions[i - 1] == "Contest":
			decisions.append("Gym")
	# gym yes, contest yes
	elif raw[i] == "3":
		if decisions[i - 1] == "Rest":
			index = i
			while True:
				# still does not meet any no in the end
				# example: yes yes, yes yes, yes yes, yes yes
				if index == n - 1:
					# choose any
					decisions.append("Gym")
					break

				# gym no, contest no
				if raw[index + 1] == "0":
					# choose any
					decisions.append("Gym")
					break
				# gym no, contest yes
				elif raw[index + 1] == "1":
					decisions.append("Gym")
					break
				# gym yes, contest no
				elif raw[index + 1] == "2":
					decisions.append("Contest")
					break
				# gym yes, contest yes
				elif raw[index + 1] == "3":
					index += 1
		elif decisions[i - 1] == "Gym":
			decisions.append("Contest")
		elif decisions[i - 1] == "Contest":
			decisions.append("Gym")

restCount = 0

for i in range(n):
	if decisions[i] == "Rest":
		restCount += 1

print(restCount)