#include <bits/stdc++.h>

using namespace std;

#define REP(i,n) for(int i=0; i<(int)(n); i++)

vector<bool> psieve(int n) {
  vector<bool> pr(n);
  for (int i = 2; i < n; i++)
    pr[i] = true;
  for (int i = 2; i * i < n; i++) {
    if (!pr[i]) continue;
    for (int j = i * i; j < n; j += i)
      pr[j] = false;
  }
  return pr;
}

int calc(int x) {
  return x % 9 ? x % 9 : 9;
}

int main() {
  ios_base::sync_with_stdio(0);
  cin.tie(0);

  int k, n;
  cin >> k >> n;

  auto p = psieve(n+1);
  vector<int> x;
  for (int i = k; i <= n; i++)
    if (p[i])
      x.push_back(i);

  vector<int> h(x.size());
  for (int i = 0; i < x.size(); i++)
    h[i] = calc(x[i]);

  int best = 0;
  int ret = 0;
  for (int i = 0; i < h.size(); i++) {
    int vis = 0;
    for (int j = i; j < h.size(); j++) {
      if (vis & 1 << h[j])
        break;
      vis |= 1 << h[j];
    }
    int cnt = __builtin_popcountll(vis);
    if (cnt >= best) {
      best = cnt;
      ret = x[i];
    }
  }

  cout << ret << endl;
  
  return 0;
}