/* -*- coding: utf-8 -*-
 *
 * 371.cc: No.371 ぼく悪いプライムじゃないよ - yukicoder
 */

#include<cstdio>
#include<cstdlib>
#include<cstring>
#include<cmath>
#include<iostream>
#include<string>
#include<vector>
#include<map>
#include<set>
#include<stack>
#include<list>
#include<queue>
#include<deque>
#include<algorithm>
#include<numeric>
#include<utility>
#include<complex>
#include<functional>
 
using namespace std;

/* constant */

const int MAX_P = 100000;

/* typedef */

typedef long long ll;
typedef vector<int> vi;

/* global variables */

bool primes[MAX_P + 1];

/* subroutines */

void gen_primes(int maxp, vi &pnums) {
  memset(primes, true, sizeof(primes));
  primes[0] = primes[1] = false;

  int p;
  for (p = 2; p * p <= maxp; p++)
    if (primes[p]) {
      pnums.push_back(p);
      for (int q = p * p; q <= maxp; q += p) primes[q] = false;
    }
  for (; p <= maxp; p++)
    if (primes[p]) pnums.push_back(p);
}

/* main */

int main() {
  vi pnums;
  gen_primes(MAX_P, pnums);
  //printf("%lu\n", pnums.size());

  ll l, h;
  cin >> l >> h;

  ll ans = 0;
  for (int i = pnums.size() - 1; i >= 0; i--) {
    ll pi = pnums[i];
    if (pi * pi > h) continue;

    ll minx = max(l, pi * pi), x;
    for (x = h; x >= minx; x--) {
      if (x % pi != 0) continue;
      ll y = x / pi;
      bool ok = true;
      for (int j = 0; ok && j < i; j++)
	ok = (y % pnums[j] != 0);
      if (ok) break;
    }
    if (x >= minx) {
      ans = x;
      break;
    }
  }

  printf("%lld\n", ans);
  return 0;
}