#include<bits/stdc++.h> #define int long long using namespace std; signed main(){ // freopen("a.in","r",stdin); // freopen("a.ans","w",stdout); int n=0,s=0,ans=0; cin>>n>>s; string ss=to_string(n); int aaa=ss.size()*9; //cout<<aaa; for(int i=s+9;i<=s+aaa+1;i++){ int c=i; int a=0; bool is=false; while(c!=0){ a+=c%10; c/=10; if(a>i-s){ is=true; break; } } if(is){ continue; } ans++; } if(s>n){ cout<<0; return 0; } cout<<ans+n-(s+aaa+1); return 0; }