def test(s):

	res = 0
	aAdd = 0
	last = ''
	tmp = ''
	for i in xrange(len(s)):
		if tmp and tmp > i:
			continue
		if s[i] == 'A':
			aAdd += 1
		elif s[i:i+2] == 'BC':
			# print aAdd
			res = res + aAdd
			tmp = i + 2
		else:
			aAdd = 0
			last = s[i]


	return res
s=raw_input()
print test(s) def test(s):

	res = 0
	aAdd = 0
	last = ''
	tmp = ''
	for i in xrange(len(s)):
		if tmp and tmp > i:
			continue
		if s[i] == 'A':
			aAdd += 1
		elif s[i:i+2] == 'BC':
			# print aAdd
			res = res + aAdd
			tmp = i + 2
		else:
			aAdd = 0
			last = s[i]


	return res test res = 0 res 0 aAdd = 0 aAdd 0 last = '' last '' tmp = '' tmp '' for i in xrange(len(s)):
		if tmp and tmp > i:
			continue
		if s[i] == 'A':
			aAdd += 1
		elif s[i:i+2] == 'BC':
			# print aAdd
			res = res + aAdd
			tmp = i + 2
		else:
			aAdd = 0
			last = s[i]


	 i xrange(len(s)) xrange len(s) len s if tmp and tmp > i:
			continue
		 tmp and tmp > i tmp tmp > i tmp i continue if s[i] == 'A':
			aAdd += 1
		elif s[i:i+2] == 'BC':
			# print aAdd
			res = res + aAdd
			tmp = i + 2
		else:
			aAdd = 0
			last = s[i]


	 s[i] == 'A' s[i] s i 'A' aAdd += 1 aAdd 1 elif s[i:i+2] == 'BC':
			# print aAdd
			res = res + aAdd
			tmp = i + 2
		 s[i:i+2] == 'BC' s[i:i+2] s i:i+2 i i+2 i 2 'BC' res = res + aAdd res res + aAdd res aAdd tmp = i + 2 tmp i + 2 i 2 aAdd = 0 aAdd 0 last = s[i] last s[i] s i return res res s s s=raw_input() s raw_input() raw_input print test(s) test s s=raw_input() raw_input() s def test(s):

	res = 0
	aAdd = 0
	last = ''
	tmp = ''
	for i in xrange(len(s)):
		if tmp and tmp > i:
			continue
		if s[i] == 'A':
			aAdd += 1
		elif s[i:i+2] == 'BC':
			# print aAdd
			res = res + aAdd
			tmp = i + 2
		else:
			aAdd = 0
			last = s[i]


	return res def test(s):

	res = 0
	aAdd = 0
	last = ''
	tmp = ''
	for i in xrange(len(s)):
		if tmp and tmp > i:
			continue
		if s[i] == 'A':
			aAdd += 1
		elif s[i:i+2] == 'BC':
			# print aAdd
			res = res + aAdd
			tmp = i + 2
		else:
			aAdd = 0
			last = s[i]


	return res test
def test(s):

	res = 0
	aAdd = 0
	last = ''
	tmp = ''
	for i in xrange(len(s)):
		if tmp and tmp > i:
			continue
		if s[i] == 'A':
			aAdd += 1
		elif s[i:i+2] == 'BC':
			# print aAdd
			res = res + aAdd
			tmp = i + 2
		else:
			aAdd = 0
			last = s[i]


	return res
s=raw_input()
print test(s)