#include <bits/stdc++.h>   using namespace std;   inline void Rd(int &res) {     char c;     res = 0;     while (c = getchar(), c <  0 )       ;     do {       res = (res << 1) + (res << 3) + (c ^ 48);     } while (c = getchar(), c >=  0 );   }   const int S = 200;   long long n, s, ans;   int work(long long x) {     int rs = 0;     while (x) {       rs += x % 10;       x /= 10;     }     return rs;   }   int main() {     cin >> n >> s;     for (int i = 1; i <= n && i <= S; i++) {       int sum = work(i);       if (abs(sum - i) >= s) ans++;     }     if (n > S) {       ans += max((long long)0, n - (s + S) + 1);       if (s < S) {         for (long long i = S + 1; i < s + S && i <= n; i++) {           int sum = work(i);           if (abs(sum - i) >= s) ans++;         }       } else {         for (long long i = s; i < s + S && i <= n; i++) {           int sum = work(i);           if (abs(sum - i) >= s) ans++;         }       }     }     cout << ans << endl;     return 0;   }   