#include<iostream>
#include<cmath>
using namespace std;
long long P(long long N)
{
  long long product = 1;
  while(N>10)
  {
    long long part = N%10;
    N = N/10;
    product *= part;
  }
  if(N>0) product *= N;
  return product;
}
long long Q(long long N)
{
  return N * P(N);
}
int main()
{
   long long L, K, R, N = 1;
   cin >> L >> K;
   long long X = L;
   while(X <= 2*K-3)
   {
       R = Q(X);
       if(L <= R && X >= K)
       {
           //cout << X << " " << " "<< R << endl;
           //break;
       }
       X++;
   }
   cout << R << endl;
   return 0;
}