#include <iostream>
#include <cstdio>
#include <numeric>
#include <algorithm>
#include <string>
#include <vector>
#include <functional>
#include <cmath>
#include <queue>

#define rep(i, a) FOR(i, 0, a)
#define FOR(i, a, b) for(int i = a; i < b; ++i)

typedef long long ll;
typedef unsigned long long ull;
typedef std::pair<int, int> P;
struct edge{ int to, time, cost; };

const int max = 200001;

bool isPrime[max];
int data[max];
bool ex[10];

int main(){
	rep(i, max)isPrime[i] = true;
	isPrime[0] = isPrime[1] = false;
	for (int i = 2; i * i <= max; ++i){
		if (isPrime[i]){
			for (int j = i * 2; j < max; j += i)isPrime[j] = false;
		}
	}

	int n, m;
	std::cin >> n >> m;
	int s = 0;
	FOR(i, n, m + 1){
		if (isPrime[i]){
			data[s] = i;
			++s;
		}
	}

	int f = 0, size = 0, ans = data[0];
	rep(i, s){
		while (ex[data[i] % 9])ex[data[f] % 9] = false, ++f;
		ex[data[i] % 9] = true;
		if (i - f + 1 >= size)size = i - f + 1, ans = data[f];
	}
	std::cout << ans << std::endl;
	return 0;
}