#include <stdio.h>
#include <string.h>

FILE *f,*s;

char v1[1000000];
int n[1000000],c[10000];
long long int m,r,d;
long int i,j;

long long int rest (int A[1000000], long long int X)  
{ 
	long long int R=0;  
      
	for (i=A[0];i;i--)  
	R=(10*R+A[i])%X;  
	return R;  
}  

void suma(int x[1000000], int y[10000])
{
	long long int T=0;
	
	if(y[0]>x[0])
	{
		for (i=x[0]+1; i<=y[0]; i++) x[i]=0;
		x[0]=y[0];
	}
    else	
		for (i=y[0]+1; i<=x[0]; i++) y[i]=0;
	
	for (i=y[0]+1; i<=x[0]; i++) y[i]=0;
	
	for (i=1;i<=x[0];i++)
	{
		x[i]+=y[i]+T;
		T=x[i]/10;
		x[i]%=10;
	}
	
	if (T)
	{
		x[0]++;
		x[x[0]]=T;
	}
}

int main()
{
	f=fopen("next.in","r");
	s=fopen("next.out","w");
	
	fscanf(f,"%s\n",&v1);
	
	n[0]=strlen(v1);
	
	j=1;
	for(i=n[0]-1;i>=0;i--)
	{
		n[j]=v1[i]-48;
		
		j++;
	}	
	
	fscanf(f,"%lld",&m);
	
	r=rest(n,m);
	
	d=m-r;
	
	c[0]=0;
	while(d)
	{
		c[0]++;
		c[c[0]]=d%10;
		d/=10;
	}	
	
	if(r==0)
	{
		for(i=n[0];i>0;i--)
			fprintf(s,"%d",n[i]);
	}
	else
	{	
		suma(n,c);
	
		for(i=n[0];i>0;i--)
			fprintf(s,"%d",n[i]);
	}
	
	fclose(s);
	
	return 0;
}