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;
const int K = 26;
int cnt[K];
int main() {
  ios_base::sync_with_stdio(0);
  cin.tie(0);
  cout.tie(0);
  long long n;
  cin >> n;
  if (n < 1e6) {
    int ans = -1;
    for (long long i = max(n / 2 - 1000000ll, 0ll); i <= n / 2 + 1000000; i++) {
      long long j = n - i;
      if (j < 0) break;
      int a = 0, b = 0;
      long long x = i, y = j;
      while (x > 0) {
        a += x % 10;
        x /= 10;
      }
      while (y > 0) {
        b += y % 10;
        y /= 10;
      }
      ans = max(ans, a + b);
    }
    cout << ans;
    return 0;
  }
  long long deg = 1;
  while (deg < n) {
    deg *= 10ll;
  }
  deg /= 10ll;
  long long x = (n / deg) * deg - 1ll;
  long long y = n - x;
  int a = 0, b = 0;
  while (x > 0) {
    a += x % 10;
    x /= 10;
  }
  while (y > 0) {
    b += y % 10;
    y /= 10;
  }
  int ans = a + b;
  cout << ans;
}