#include <iostream>
#include <vector>
#include <string>
#include <stack>
#include <queue>
#include <deque>
#include <set>
#include <map>
#include <algorithm>	// require sort next_permutation count __gcd reverse etc.
#include <cstdlib>	// require abs exit atof atoi 
#include <cstdio>		// require scanf printf
#include <functional>
#include <numeric>	// require accumulate
#include <cmath>		// require fabs
#include <climits>
#include <limits>
#include <cfloat>
#include <iomanip>	// require setw
#include <sstream>	// require stringstream 
#include <cstring>	// require memset
#include <cctype>		// require tolower, toupper
#include <fstream>	// require freopen
#include <ctime>		// require srand
#define rep(i,n) for(int i=0;i<(n);i++)
#define ALL(A) A.begin(), A.end()
/*
	No.6 使いものにならないハッシュ

	エラトエラトネスの篩、しゃくとり法

	蟻本 p135〜
*/
using namespace std;

typedef long long ll;
typedef pair<int, int> P;

const int MAX_N = 200008;

bool p[MAX_N];
vector<int> prime;

void sieve(int K, int N ){
	fill (p, p+MAX_N, true );
	p[0] = false;
	p[1] = false;
	
	for (int i = 2; i < MAX_N; i++ ){
		if (p[i] ){
			for (int j = 2*i; j < MAX_N; j += i ){
				p[j] = false;
			} // end for
		} // end if
	} // end for

	prime.clear();
	for (int i = K; i <= N; i++ ){
		if (p[i] ) prime.push_back (i );
	} // end for
}

int cnt[10];

int main()
{
	memset (cnt, 0, sizeof (cnt ) );
	ios_base::sync_with_stdio(0);
	int K, N; cin >> K >> N;
	sieve(K, N );

	int res = 0, curr = 0;
	int j = 0;
	rep (i, prime.size() ){
		while (j < prime.size() && cnt[prime[j]%9] == 0 ){
			cnt[prime[j]%9]++;
			j++;
		} // end while
		if (curr <= j - i ){
			curr = j - i;
			res = prime[i];
		} // end if
		cnt[prime[i]%9]--;
	} // end rep

	cout << res << endl;

	return 0;
}