#include<cstdio>
#include<cstring>
#include<algorithm>
using namespace std;
char s[1000105];
int a[1000105];
int b[1000105];
long long modulo(long long d)
{
    long long r=0,i;
    for(i=a[0]; i>=1; i--)
        r=(r*10+a[i])%d;
    return r;
}
void adunh(int a[],int b[])
{
    int i,tr,aux,l;
    tr=0;
    l=max(a[0],b[0]);
    a[0]=l;
    for(i=1; i<=a[0]; i++)
    {
        aux=a[i]+b[i]+tr;
        a[i]=aux%10;
        tr=aux/10;
    }
    while(tr)
    {
        a[++a[0]]=tr%10;
        tr=tr/10;
    }
}
int main()
{
    freopen("next.in","r",stdin);
    freopen("next.out","w",stdout);
    int i,n;
    long long r,d;
    gets(s);
    n=strlen(s);
    for(i=n-1; i>=0; i--)
        a[n-i]=s[i]-'0';
    a[0]=n;
    scanf("%lld",&d);
    r=modulo(d);
    r=d-r;
    if(r==d)
        r=0;
    do
    {
        b[++b[0]]=r%10;
        r=r/10;
    }while(r);
    adunh(a,b);
    for(i=a[0]; i>=1; i--)
        printf("%d",a[i]);
    return 0;
}