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 CPP):

Solution:
#include <bits/stdc++.h>
using namespace std;
long long int add(long long int n) {
  long long int s = 0;
  while (n > 0) {
    s = s + n % 10;
    n /= 10;
  }
  return s;
}
void solve() {
  long long int n, m, k, d, k1, k2, k3;
  cin >> n;
  if (n % 10 == 0) {
    k = n / 2;
    d = k + 1;
    m = k - 1;
    cout << add(d) + add(m) << endl;
  } else {
    k = 0;
    while (k * 10 + 9 <= n) {
      k = k * 10 + 9;
    }
    cout << add(k) + add(n - k) << endl;
  }
}
int main() {
  solve();
  return 0;
}