func_code_string: #include <bits/stdc++.h>   const long long oo = 1e16;   using namespace std;   const int N = 1000005;   long long n, dp[N];   long long num(long long n) {     if (n == 0) return 0;     if (dp[n] != -1) return dp[n];     string s = to_string(n);     long long res = oo;     for (int i = 0; i < s.size(); i++)       if (s[i] !=  0 ) res = min(res, 1 + num(n - (s[i] -  0 )));     return dp[n] = res;   }   int main() {     cin >> n;     memset(dp, -1, sizeof(dp));     cout << num(n);     return 0;   }   