#include <algorithm>
#include <iostream>
#include <vector>
#include <map>
using namespace std;

vector<long long> getPrimes(int n) {
  vector<bool> ok(n, true);
  ok[0] = ok[1]= false;
  vector<long long> ret;
  for (int i = 2; i < n; i++) {
    if (!ok[i])
      continue;
    ret.push_back(i);
    for (int j = i; j < n; j += i)
      ok[j] = false;
  }
  return ret;
}

long long fac(long long x) {
  for (long long d = 2; d * d <= x; d++) {
    if (x % d == 0)
      return d;
  }
  return x;
}

int main(int argc, char *argv[])
{
  long long l, h;
  cin >> l >> h;

  pair<long long, long long> ret = make_pair(0, 0);
  vector<long long> ps = getPrimes(1e6);
  for (int i = ps.size()-1; i >= 0; i--) {
    if (ps[i] < ret.first) break;
    long long x = h / ps[i] * ps[i];
    while (l <= x) {
      long long d = min(ps[i], fac(x/ps[i]));
      ret = max(ret, make_pair(d, x));
      x -= ps[i];
    }
  }
  cout << ret.second << endl;
  
  return 0;
}