#include <bits/stdc++.h>
using namespace std;
 
using ll = long long; using ld = long double; using ull = unsigned long long; using uint = unsigned int;
using vi  = vector<int>; using vb  = vector<bool>; using vd  = vector<double>; using vl  = vector<ll>;
using vvi = vector<vi>;  using vvb = vector<vb>;   using vvd = vector<vd>;     using vvl = vector<vl>;
 
#define REP(i,n) for(ll i=0; i<(n); ++i)
#define FOR(i,b,n) for(ll i=(b); i<(n); ++i)
#define ALL(v) (v).begin(), (v).end()
#define TEN(x) ((ll)1e##x)
 
template<typename T> inline string join(const vector<T>& vec, string sep = " ") { stringstream ss; REP(i, vec.size()) ss << vec[i] << ( i+1 == vec.size() ? "" : sep ); return ss.str(); }

vb eratosthenes(ll n) {
	vb t(n+1, true); t[0] = t[1] = false;
	for(ll i = 2; i <= n; ++i) if (t[i]){
		for(ll j = 2*i; j <= n; j += i) t[j] = false;
	}
	return t;
}
vl compress(const vb & t) {
	vl v; v.reserve((ll)(1.2 * t.size() / log(t.size())));
	REP(i, t.size()) if (t[i]) v.push_back(i);
	return v;
}

ll min_prime(ll n) {
	ll x = sqrt(n);
	FOR(i, 2, x+1) if (n%i == 0) return i;
	return 1;
}

int main() {
#ifdef INPUT_FROM_FILE
	ifstream cin("sample.in");
	ofstream cout("sample.out");
#endif
	cin.tie(0);
	ios_base::sync_with_stdio(false);
	cout << fixed << setprecision(30);
	ll n, m; cin >> n >> m;

	auto e = eratosthenes(sqrt(m)*50);
	auto er = compress(e);
	ll index = er.size() - 1;
	while (index >= 0 && er[index] * er[index] > m) index--;

	while (index>0) {
		ll ma = -1;
		for (ll i = index; i < er.size() && er[i] * er[index] <= m; ++i) {
			if(er[i] * er[index] >= n) ma = er[i] * er[index];
		}
		if (ma != -1) {
			cout << ma << endl;
			return 0;
		}
		index--;
	}
	

	ll ma = 1;
	ll mai = 1;
	for (ll i = m; i >= n; --i) {
		ll x = min_prime(i);
		if (ma < x) {
			ma = x;
			mai = i;
		}
	}

	cout << mai << endl;
	return 0;
}