#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 minfac(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;

  vector<long long> ps = getPrimes(150000);
  for (int i = ps.size()-1; i >= 0; i--) {
    long long x = h / ps[i] * ps[i];
    long long lb = max(l, ps[i] * ps[i]);
    while (x >= lb) {
      long long d = minfac(x / ps[i]);
      if (d > ps[i]) {
        cout << x << endl;
        return 0;
      }
      x -= ps[i];
    }
  }

  throw;
}