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