#include <bits/stdc++.h>

#define mp       make_pair
#define mt	 make_tuple
#define pb       push_back
#define rep(i,n) for(int i=0;i<(n);i++)

using namespace std;

typedef    long long          ll;
typedef    unsigned long long ull;
typedef    pair<int,int>      pii;
typedef    pair<long,long>    pll;

const int INF=1<<29;
const double EPS=1e-9;
const int MOD = 100000007;

const int dx[]={1,0,-1,0},dy[]={0,-1,0,1};
const int MAX_N = 100002;
bool is_prime[MAX_N];
vector<int> primes;
void gen_prime(){
  memset(is_prime, true, sizeof(is_prime));
  is_prime[0] = false;
  is_prime[1] = false;
  for (int i = 2; i < MAX_N; i++){
    if (not is_prime[i])continue;
    primes.push_back(i);
    for (int j = i + i; j < MAX_N; j += i){
      is_prime[j] = false;
    }
  }
  return ;
}
#ifdef _MSC_VER
#include <Windows.h>
double get_ms() { return (double)GetTickCount64() / 1000; }
#else
#include <sys/time.h>
double get_ms() { struct timeval t; gettimeofday(&t, NULL); return (double)t.tv_sec * 1000 + (double)t.tv_usec / 1000; }
#endif

class Timer
{
private:
  double start_time;
  double elapsed;

#ifdef USE_RDTSC
  double get_sec() { return get_absolute_sec(); }
#else
  double get_sec() { return get_ms() / 1000; }
#endif

public:
  Timer() {}

  void start() { start_time = get_sec(); }
  double get_elapsed() { return elapsed = get_sec() - start_time; }
};
ll L,H;
unordered_set<ll> flag;
Timer timer;
ll max_value;
void get_max_value(ll val, int index){
  if (timer.get_elapsed() > 3)return ;
  if (val > H)return ;
  if (flag.size() > 0 and L <= val and val <= H){
    //    cout << val << endl;
    max_value = max(max_value, val);
  }
  flag.insert(val);
  for (int i = index; i < primes.size(); i++){
    if (val * primes[i] <= H){
      if (flag.count(val * primes[i]) > 0)continue;
      get_max_value(val * primes[i], index);
    }
  }
}

ll result;
int main(){
  cin >> L >>H;
  gen_prime();
  result = 0;
  sort(primes.begin(), primes.end());

  for (int i = primes.size() - 1; i >=0; i--){
    flag.clear();
    max_value = 0;
    timer.start();
    get_max_value(primes[i], i);
    if (max_value != 0){
      break;
    }

  }

  cout << max_value << endl;
}