N = input()
i = len(N)
if i < 9:
	print(0)
else:
	A = N[:-9]
	a = (len(A) - 1) * 9
	a = a + int(A[0]) - 1
	if 1 < len(A) and int(A[1]) > int(A[0]):
		a = a + 1
	elif int(N) >= int(A[0] * len(A) + "0" * 9) + int(A[0] * len(A)):
		a = a + 1
	print(a)