#include <bits/stdc++.h>

using namespace std;
typedef long long ll;
typedef pair<ll, ll> p_ll;

template<class T>
void debug(T itr1, T itr2) { auto now = itr1; while(now<itr2) { cout << *now << " "; now++; } cout << endl; }
#define repr(i,from,to) for (int i=(int)from; i<(int)to; i++)
#define all(vec) vec.begin(), vec.end()
#define rep(i,N) repr(i,0,N)
#define per(i,N) for (int i=(int)N-1; i>=0; i--)

const ll MOD = pow(10,9)+7;
const ll LLINF = pow(2,61)-1;
const int INF = pow(2,30)-1;

vector<ll> fac;
void c_fac(int x=pow(10,6)+10) { fac.resize(x,true); rep(i,x) fac[i] = i ? (fac[i-1]*i)%MOD : 1; }
ll inv(ll a, ll m=MOD) { ll b = m, x = 1, y = 0; while (b!=0) { int d = a/b; a -= b*d; swap(a,b); x -= y*d; swap(x,y); } return (x+m)%m; }
ll nck(ll n, ll k) { return fac[n]*inv(fac[k]*fac[n-k]%MOD)%MOD; }
ll gcd(ll a, ll b) { if (a<b) swap(a,b); return b==0 ? a : gcd(b, a%b); }
ll lcm(ll a, ll b) { return a/gcd(a,b)*b; }

// ----------------------------------------------------------------------
// ----------------------------------------------------------------------

vector<bool> isp;

void sieve(int x=pow(10,6)+10) {
  isp.resize(x,true); 
  isp[0] = false;
  isp[1] = false;
  for (int i=2; pow(i,2)<=x; i++) {
    if (isp[i]) for(int j=2; i*j<=x; j++) isp[i*j] = false;
  }
}

// ----------------------------------------------------------------------
// ----------------------------------------------------------------------

int main() {
  sieve();
  int K, N; cin >> K >> N;

  vector<int> hash; repr(i,K,N+1) if (isp[i]) hash.push_back(i);
  // debug(all(hash));
  int l = 0, len = 1, result = hash[0];
  set<int> num; num.insert(hash[0]%9);
  repr(r,1,hash.size()) {
    if (num.count(hash[r]%9)) {
      while(hash[l]%9!=hash[r]%9) {
        num.erase(hash[l]%9);
        l++;
      }
      l++;
    }
    if (len<=r-l+1) { len = r-l+1; result = hash[l]; }
    // cout << l << "->" << r << endl;
  }
  cout << result << endl;
  return 0;
}