#include <iostream>
#include <vector>
#include <array>
#include <algorithm>
#include <string>
#include <map>
#include <queue>
#include <iomanip>
#include <numeric>
#include <memory>
#include <limits.h>
#include <set>
#include <cassert>
#include <cmath>
#include <bitset>
#include <functional>
#include <limits>
using namespace std;

typedef long long ll;

#define REP(i,n) for(ll i=0; i<(n); ++i)
#define TEN(x) ((ll)1e##x)
#define ALL(v) (v).begin(), (v).end()

// [a,b)の整数に対して篩 O((b-a) log log b): is_prime[i-a] = true ⇔ iが素数
vector<int> segment_sieve(ll a, ll b){
	vector<int> t_small(sqrt(b)+1, true);
	vector<int> t(b-a, true);
	
	for(ll i = 2; i*i < b; ++i) if(t_small[i]){
		for(ll j = 2*i; (ll)j*j < b; j+=i) t_small[j] = false;  // [2, √b)の篩
		for(ll j = max(2LL, (a+i-1)/i) * i; j < b; j+=i) t[j - a] = false; // [a,b)の篩
	}
	
	return t;
}

// 数字根
// 345 -> 3+4+5 = 12 -> 1+2 = 3 ≡ 345 (mod 9)
ll numroot(ll a){
	if(a!=0 && a%9==0) return 9;
	return a%9;
}

int main(){
	ll k, n;
	cin >> k >> n;
	auto t = segment_sieve(k, n + 1); 
	vector<ll> v; v.reserve(t.size());
	REP(i, t.size()) if (t[i] && i+k!=1) v.push_back(i + k);
	vector<ll> r(v.size());
	REP(i, v.size()) r[i] = numroot(v[i]);
	
	vector<bool> used(10, false);
	vector<ll> max_l(11, -1);
	ll end = v.size();
	for (ll i = v.size() - 1; i >= 0; --i) {
		while (used[r[i]]) {
			end--;
			used[r[end]] = false;
		}
		used[r[i]] = true;
		if (max_l[end - i] == -1) max_l[end - i] = v[i];
	}
	reverse(ALL(max_l));
	for (auto x : max_l) if (x != -1) {
		cout << x << endl;
		return 0;
	}
}