#include <fstream>
#include <algorithm>
#include <cstring>
using namespace std;
const int NMAX=1000005;
ifstream fin ("next.in");
ofstream fout ("naxt.out");
long long div_h_long (int a[], long long k)
{
    long long i,r;
    r=0;
    for(i=a[0];i>=1;i--)
    {
        r=r*10+a[i];
        r=r%k;
    }
        return r;
}
void print (int c[])
{
    int i;
    for(i=c[0];i>=1;i--)
        fout<<c[i];
    fout<<"\n";
}
void adun (int a[],int b[],int c[NMAX])
{
    int i,tr,aux;
    memset(c,0,sizeof(c));
    c[0]=max(a[0],b[0]);
    tr=0;
   for(i=1;i<=c[0];i++)
   {
       aux=a[i]+b[i]+tr;
       c[i]=aux%10;
       tr=aux/10;
   }
   if(tr)
    c[++c[0]]=tr;
}
int main()
{
char ch;
int a[NMAX],c[NMAX];
long long d,r;
memset (a,0,sizeof(a));
ch=fin.get();
while(ch!='\n')
{
    if(ch>='0' && ch<='9')
        a[++a[0]]=ch-'0';
    ch=fin.get();
}
fin>>d;
r=div_h_long (a,d);
r=d-r;
int b[30];
memset (b,0,sizeof(b));
do
{
    b[++b[0]]=r%10;
    r=r/10;
}while(r>0);
adun(a,b,c);
print (a);
return 0;
}