#include<iostream>
#include<vector>
#include<algorithm>
#include<functional>
#include<set>

int hash(int v)
{
	if (v < 10)
	{
		return v;
	}
	else
	{
		int n = 0;
		while (v != 0)
		{
			n += v % 10;
			v /= 10;
		}
		return hash(n);
	}
}

int main()
{
	int K, N;
	std::cin >> K >> N;
	std::vector<int> primes = { 2,3,5,7 };
	for (int i = 11; i <= N; ++i)
	{
		for (auto p : primes)
		{
			if (p*p > i)
			{
				break;
			}
			else if (i%p == 0)
			{
				goto next;
			}
		}
		primes.emplace_back(i);
	next:;
	}
	std::vector<int> hashes(primes.size());
	for (std::size_t i = 0; i < primes.size(); ++i)
	{
		hashes[i] = hash(primes[i]);
	}
	int maxlength = 0;
	int maxstart = 0;
	int nowstart = std::lower_bound(primes.begin(), primes.end(), K) - primes.begin();
	std::vector<int> smallset(10);
	int count = 0;
	for (std::size_t i = nowstart; i < primes.size(); ++i)
	{
		auto h = hashes[i];
		while (smallset[h])
		{
			smallset[hashes[nowstart]] = false;
			++nowstart;
			--count;
		}
		smallset[h] = true;
		++count;
		if (maxlength <= count)
		{
			maxstart = nowstart;
			maxlength = count;
		}
	}
	std::cout << primes[maxstart] << std::endl;
}