#include <cstdio>
#include <cstring>

#define NMax 1000005
#define LL long long

using namespace std;

LL N[NMax], M;

inline LL Modulo (LL A[], LL B)
{
	LL Mod=0;
	for (int i=A[0]; i>0; --i)
	{
		Mod=(10*Mod+A[i])%B;
	}
	return Mod;
}

inline void Add (LL A[], LL B)
{
	int i, T=B;
	for (i=1; i<=A[0] or T>0; ++i, T/=10)
	{
		T+=A[i]; A[i]=T%10;
	}
	A[0]=i-1;
}

void Read ()
{
	freopen ("next.in", "r", stdin);
	char Number[NMax]; memset (Number, 0, sizeof (Number));
	scanf ("%s\n%I64d", Number, &M);
	N[0]=strlen (Number);
	for (int i=0; N[0]>0; --N[0], ++i)
	{
		N[N[0]]=Number[i]-'0';
	}
	N[0]=strlen (Number);
}

void Print ()
{
	freopen ("next.out", "w", stdout);
	for (int i=N[0]; i>0; --i)
	{
		printf ("%I64d", N[i]);
	}
	printf ("\n");
}

int main ()
{
	Read ();
	Add (N, M-Modulo (N, M));
	Print ();
	return 0;
}