#include <cmath>
#include <map>
#include <string>
#include <vector>
#include <set>
#include <algorithm>
#include <iostream>
using namespace std;
#define repi(_I, _B, _E) for(int _I = (_B); (_I) < (_E); ++ (_I))
#define rep(_I, _N) for(int _I = 0; (_I) < (_N); ++ (_I))
#define all(_X) (_X).begin(), (_X).end()

int hf(int a) {
	while ( a >= 10 ) {
		int x = 0;
		while ( a > 0 ) {
			x += a % 10;
			a /= 10;
		}
		a = x;
	}
	return a;
}

bool is_prime[200000+1];

int k, n;
void next_prime(int& a) {
	do { ++a; } while (!is_prime[a] && a < n);
	return;
}

int main() {
	cin >> k >> n;
	++n;

	//ふるい
	fill(is_prime, is_prime + n, true);
	is_prime[0] = is_prime[1] = false;
	for ( int i = 2; i * i < n; ++ i) {
		if ( is_prime[i] ) {
			for ( int j = 2; i * j < n; ++j ) {
				is_prime[i * j] = false;
			}
		}
	}

	//しゃくとり
	int s = k - 1; next_prime(s);
	int t = s;
	int maxlen = 0, p = 0;
	int len = 0;
	bool hs[10] {};
	while (t < n) {
		while (t < n && !hs[hf(t)]) {
			hs[hf(t)] = true;
			len++;
			next_prime(t);
		}

		if ( maxlen <= len ) {
			maxlen = len;
			p = s;
		}

		len--;
		hs[hf(s)] = false;
		next_prime(s);
	}
	cout << p << endl;
	return 0;
}