#include <iostream>
#include <fstream>
#include <cstring>
#define ll long long
using namespace std;
ifstream f ("next.in");
ofstream g ("next.out");

char v[1000010];
ll d;

int Mod(char v[], ll d)
{
    ll r=0;
    for (unsigned i=0;i<strlen(v);i++)
    {
        r=r*10+v[i]-'0';
        r%=d;
    }
    return r;
}
int main()
{
    f.getline(v,1000005);
    f>>d;
    ll r=Mod(v,d);
    for (int i=strlen(v)-1;i>=0;i--)
    {
        v[i]=v[i]-r%10;
        if (v[i]<'0') v[i-1]--,v[i]+=10;
        r/=10;
    }
    g<<v;
    return 0;
}