#include <bits/stdc++.h>
using namespace std;

int main() {
  int K, N;
  cin >> K >> N;
  vector<bool> B(N + 1, 1);
  B.at(0) = B.at(1) = 0;
  for (long i = 2; i <= N; i++) if (B.at(i)) for (long j = i * i; j <= N; j += i) B.at(j) = 0;
  vector<int> P;
  for (int i = K; i <= N; i++) if (B.at(i)) P.push_back(i);
  vector<int> V(9);
  int ans = 0;
  for (int l = 0, r = 0, b = 0, mx = 0; r < P.size(); r++) {
    if (++V.at(P.at(r) % 9) == 2) b = 1;
    while (b) if (--V.at(P.at(l++) % 9) == 1) b = 0;
    if (r - l >= mx) mx = r - l, ans = P.at(l);
  }
  cout << ans << "\n";
}