#include<bits/stdc++.h>
using namespace std;
int tong(int n){
int sum=0;
int temp=n;
while(n!=0){
sum+=n%10;
n/=10;
}
return sum+temp;
}
int main(){
int n,m;
cin>>n>>m;
int dem=1;
int x=tong(n);
while(x<=m){
dem++;
x=tong(x);
}
cout<<dem;
}
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