#include <bits/stdc++.h>
using namespace std;
int main(){
  int K;
  cin >> K;
  int N;
  cin >> N;
  vector<bool> prime(N + 1, true);
  prime[0] = false;
  prime[1] = false;
  for (int i = 2; i <= N; i++){
    if (prime[i]){
      for (int j = i * 2; j <= N; j += i){
        prime[j] = false;
      }
    }
  }
  vector<int> p;
  for (int i = K; i <= N; i++){
    if (prime[i]){
      p.push_back(i);
    }
  }
  int M = p.size();
  int ans1 = 0;
  int ans2 = 0;
  for (int i = 0; i < M; i++){
    set<int> st;
    for (int j = i; j < M; j++){
      int h = (p[j] - 1) % 9 + 1;
      if (st.count(h)){
        break;
      }
      st.insert(h);
      int d = j - i + 1;
      if (d >= ans1){
        ans2 = p[i];
        ans1 = d;
      }
    }
  }
  cout << ans2 << endl;
}