#include<cstdio>
#include<iostream>
#include<algorithm>
#include<cmath>
#include<cstdlib>
#include<queue>
#include<map>
#include<set>
#include<string>
#include<sstream>
#include<climits>
#include<vector>
#include<cstring>
#include<stack>

using namespace std;

#define REP(i,s,n)  for (int i=(s),_n=(n);i<=_n;i++)
#define FOR(i,s,n)  for (int i=(s),_n=(n);i<_n;i++)
#define REPD(i,e,s)  for (int i=(e),_s=(s);i>=_s;i--)
#define tr(container, it) \
		        for (typeof(container.begin()) it=container.begin(); it!=container.end();it++)
#define PB push_back

typedef long long LL;
typedef vector<int> VI;
typedef pair<int,int> PI;

long long int ans=0;

int main() {
	long long int a,b;
	cin >>a >> b;
	ans=a;
	long long int cpy=a,t=0;
	while(b>0)
	{
		if( a%10 ==9)
		{
			a/=10;
			b/=10;
		}
		else
		{
			if(a%10+1 <=b)
			{
				
				cpy-=(a%10+1)* (long long int) (pow((long long int)10,t));
				b-=a%10+1;
				a-=a%10+1;
				a/=10;
				b/=10;
			}
			else
				break;
		}
		t+=1;
	}
	cout<<cpy<<endl;
	return 0;
}