#include<cstdio>
#include<cstdlib>
#include<cstring>
#define N 25
#define ri register int
#define fo(i,l,r) for(ri i=l;i<=r;i++)
#define rf(i,r,l) for(ri i=r;i>=l;i--)
#define ul unsigned long long
using namespace std;
ul n,m,k,ten[N],dp[N],num[N];
void swap(int &x,int &y){int t=x;x=y;y=t;}
int max(int x,int y){return x>y?x:y;}
int min(int x,int y){return x<y?x:y;}
int abs(int x){return x<0?-x:x;}
void init(){
	ten[0]=1;
	fo(i,1,20)dp[i]=i*ten[i-1],ten[i]=ten[i-1]*10;
}
ul gs(ul x)
{
	ul n=0,ans=0;
	while(x)num[++n]=x%10,x/=10;
	rf(i,n,1)
	{
		ans+=dp[i-1]*num[i];
		if(num[i])ans+=ten[i-1];
		ul sum=0;
		fo(j,i-1,1)sum=sum*10+num[j];
		if(!num[i])ans+=sum+1;
		ans-=ten[i-1];
	}
	return ans+1;
}
int read(){
    int sum=0;bool f=0;char c=getchar();
    for(;c<48||c>57;c=getchar())if(c==45)f=1;
    for(;c>=48&&c<=57;c=getchar())sum=sum*10+(c&15);
    return f?-sum:sum;
}
int main(){
    freopen("whz_number.in","r",stdin);freopen("whz_number.out","w",stdout);
    init();
    while(~scanf("%llu%llu",&n,&k))
    {
    	m=gs(n);
    	ul l=0,r=n,mid;
    	while(l<r)
    	{
    		mid=l+(r-l+1>>1);
    		if(m-gs(mid-1)>=k)l=mid;
    		else r=mid-1;
		}
		printf("%llu\n",l);
	}
    return 0;
}