#include <algorithm>
#include <iostream>
#include <vector>
#include <numeric>
using namespace std;

int digital_root(int n, int base = 10) {
    if (n == 0) return 0;
    if (n % (base - 1) == 0) return base - 1;
    return n % (base - 1);
}

vector<int> prime_table(int n) {
    vector<int> is_prime(n + 1);
    if (n) iota(is_prime.begin() + 2, is_prime.end(), 2);
    for (int i = 2; i * i <= n; i++) if (is_prime[i]) {
        for (int j = i + i; j <= n; j += i) is_prime[j] = 0;
    }
    return is_prime;
}

int main() {
    int k; cin >> k;
    int n; cin >> n;
    auto is_prime = prime_table(n);
    vector<int> ps, ds;
    for (int x = k; x <= n; x++) if (is_prime[x]) ps.emplace_back(x);
    for (auto &p: ps) ds.emplace_back(digital_root(p));
    pair<int, int> ma{-1, -1};
    for (int i = 0, sz = ps.size(); i < sz; i++) {
        int cur = i, mask = 0;
        while (cur < sz && !(mask >> ds[cur] & 1)) mask ^= 1 << ds[cur], cur++;
        ma = max(ma, {cur - i, ps[i]});
    }
    cout << ma.second << endl;
    return 0;
}