#include <cstdio>
#include <cstring>
using namespace std;
int N[1000009], M[1000009], X[50];
long long D,x;

inline long long mod(int A[], long long B)
{
      long long t=0;
      for (int i = A[0]; i > 0; i--)
              t = (t * 10 + A[i]) % B;
      return t;
}

void add(int A[], int B[])
{
      int i, t = 0;
      for (i=1; i<=A[0] || i<=B[0] || t; i++, t/=10)
              A[i] = (t += A[i] + B[i]) % 10;
      A[0] = i - 1;
}

int main()
{
    freopen("next.in", "r", stdin);
    freopen("next.out", "w", stdout);
    char V[1000009], W[20];
    fgets(V+1, 1000009, stdin);
    N[0]=strlen(V+1)-1;
    for(int i=1; i<=N[0]; i++) N[N[0]+1-i]=(V[i]-'0');

    scanf("%lld", &D);

    x=mod(N,D);
    if (x) x=D-x;
    while(x) X[++X[0]]=x%10, x/=10;
    add(N,X);
    for(int i=N[0]; i>0; i--) printf("%d",N[i]);
    return 0;

}