#include <iostream>
#include <vector>
#include <cstdio>
#include <sstream>
#include <map>
#include <string>
#include <algorithm>
#include <queue>
#include <cmath>
#include <functional>
#include <set>
#include <ctime>
#include <random>
#include <chrono>
#include <cassert>
using namespace std;

namespace {
  using Integer = long long; //__int128;
  template<class T> istream& operator >> (istream& is, vector<T>& vec){for(T& val: vec) is >> val; return is;}
  template<class T> istream& operator ,  (istream& is, T& val){ return is >> val;}
  template<class T> ostream& operator << (ostream& os, const vector<T>& vec){for(int i=0; i<vec.size(); i++) os << vec[i] << (i==vec.size()-1?"":" "); return os;}
  template<class T> ostream& operator ,  (ostream& os, const T& val){ return os << " " << val;}

  template<class H> void print(const H& head){ cout << head; }
  template<class H, class ... T> void print(const H& head, const T& ... tail){ cout << head << " "; print(tail...); }
  template<class ... T> void println(const T& ... values){ print(values...); cout << endl; }

  template<class H> void eprint(const H& head){ cerr << head; }
  template<class H, class ... T> void eprint(const H& head, const T& ... tail){ cerr << head << " "; eprint(tail...); }
  template<class ... T> void eprintln(const T& ... values){ eprint(values...); cerr << endl; }

  string operator "" _s (const char* str, size_t size){ return move(string(str)); }
  constexpr Integer my_pow(Integer x, Integer k, Integer z=1){return k==0 ? z : k==1 ? z*x : (k&1) ? my_pow(x*x,k>>1,z*x) : my_pow(x*x,k>>1,z);}
  constexpr Integer my_pow_mod(Integer x, Integer k, Integer M, Integer z=1){return k==0 ? z%M : k==1 ? z*x%M : (k&1) ? my_pow_mod(x*x%M,k>>1,M,z*x%M) : my_pow_mod(x*x%M,k>>1,M,z);}
  constexpr unsigned long long operator "" _ten (unsigned long long value){ return my_pow(10,value); }

  inline int k_bit(Integer x, int k){return (x>>k)&1;} //0-indexed

  mt19937 mt(chrono::duration_cast<chrono::nanoseconds>(chrono::steady_clock::now().time_since_epoch()).count());

  template<class T> string join(const vector<T>& v, const string& sep){
    stringstream ss; for(int i=0; i<v.size(); i++){ if(i>0) ss << sep; ss << v[i]; } return ss.str();
  }
}

constexpr long long mod = 9_ten + 7;

vector<long long> Eratosthenes(long long N){
  vector<bool> v(N+1, true);
  v[0] = v[1] = false;
  long long sqN = sqrt(N);
  for(int i=2; i<=sqN; i++){
    if(v[i] == false) continue;
    for(long long j=i*i; j<=N; j+=i){
      v[j] = false;
    }
  }
  vector<long long> Prime;
  for(long long i=2; i<=N; i++){
    if(v[i]==true) Prime.push_back(i);
  }
  return Prime;
}

int main(){
  long long l,h;
  cin >> l,h;

  auto p = Eratosthenes(sqrt(h) + 1);
  sort(p.begin(), p.end());

  long long ans = -1;
  for(int i=0; i<p.size(); i++){
    long long a = p[p.size()-1-i];

    if(h/a - (l-1)/a <= 0) continue;
    for(long long x=(h/a)*a; x>=l; x-=a){
      long long y = x/a;
      if(y < a) break;

      bool unko=false;

      for(long long b : p){
        if(b>=a) break;
        if(y%b==0){
          unko = true;
          break;
        }
      }

      if(!unko){
        println(x);
        return 0;
      }
    }
  }

  assert(ans != -1);
  println(ans);
  return 0;
}