Problem: You are given a positive integer n.

Let S(x) be sum of digits in base 10 representation of x, for example, S(123) = 1 + 2 + 3 = 6, S(0) = 0.

Your task is to find two integers a, b, such that 0 ≤ a, b ≤ n, a + b = n and S(a) + S(b) is the largest possible among all such pairs.

Input

The only line of input contains an integer n (1 ≤ n ≤ 10^{12}).

Output

Print largest S(a) + S(b) among all pairs of integers a, b, such that 0 ≤ a, b ≤ n and a + b = n.

Examples

Input

35


Output

17


Input

10000000000


Output

91

Note

In the first example, you can choose, for example, a = 17 and b = 18, so that S(17) + S(18) = 1 + 7 + 1 + 8 = 17. It can be shown that it is impossible to get a larger answer.

In the second test example, you can choose, for example, a = 5000000001 and b = 4999999999, with S(5000000001) + S(4999999999) = 91. It can be shown that it is impossible to get a larger answer.

Solution (in PYTHON):

Solution:
def s(n):
  res = 0
  for c in str(n):
    res += int(c)
  return res

def score((a, b)):
  return s(a) + s(b)

def brut(n):
  best = (0, n)
  for i in range(n):
    cur = i, n-i
    if score(cur) > score(best):
      best = cur
  a, b = best
  #  print a, b, a+b, score((a, b))
  return score((a, b))

def sol(n):
  a = 0
  best = (0, n)
  while True:
    a = a*10 + 9
    if a > n: break
    cur = a, n-a
    if score(cur) > score(best):
      best = cur
  a, b = best
  #  print a, b, a+b, score((a, b))
  return score((a, b))

def test():
  for i in range(100000):
    assert brut(i) == sol(i)

if __name__ == '__main__':
  n = int(raw_input().strip())
  print sol(n)