#include <bits/stdc++.h>
using namespace std;
 
int h(int n){
	return n % 9;
}
 
bool isp[200010];
vector<int> getPrimes(int K, int N){
	for(int i=0;i<=N;i++)isp[i] = true;
 
	isp[0] = isp[1] = false;
	for(int p=2;p*p<=N;p++)if(isp[p]){
		for(int kp=p*p;kp<=N;kp+=p)isp[kp] = false;
	}
 
	vector<int> res;
	for(int i=K;i<=N;i++)if(isp[i])res.push_back(i);
 
	return res;
}
 
int main() {
	int K, N;
	cin >> K >> N;
 
	vector<int> primes = getPrimes(K, N);
 
	int maxi = 0;
	int res = 0;

	int used = 0;
	int last = 0;
	int cnt = 0;
	for(int i=0;i<primes.size();i++){
		while(last < primes.size()){
			int hs = h(primes[last]);
			if((used >> hs) & 1){
				break;
			} else {
				++cnt;
				used |= 1 << hs;

				++last;
			}
		}
 
		if(cnt >= maxi){
			maxi = cnt;
			res = primes[i];
		}

		int fh = h(primes[i]);
		used ^= 1 << fh;
		--cnt;
	}
 
	cout << res << endl;
	return 0;
}