#define _CRT_SECURE_NO_WARNINGS
//#define _GLIBCXX_DEBUG
#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef vector<int> vi;
typedef vector<vi> vvi;
typedef pair<int,int> pii;
#define all(c) (c).begin(), (c).end()
#define loop(i,a,b) for(ll i=a; i<ll(b); i++)
#define rep(i,b) loop(i,0,b)
#define pb push_back
#define eb emplace_back
#define mp make_pair
#define mt make_tuple
template<class T> istream& operator>>(istream& is, vector<T>& v);
template<class T> ostream& operator<<(ostream& os, vector<T> const& v);
template<int n, class...T> typename enable_if<(n>=sizeof...(T))>::type _ot(ostream&, const tuple<T...>&){}
template<int n, class...T> typename enable_if<(n< sizeof...(T))>::type _ot(ostream& os, const tuple<T...>& t){ os << (n==0?"":" ") << get<n>(t); _ot<n+1>(os, t); }
template<class...T> ostream& operator<<(ostream& os, const tuple<T...>& t){ _ot<0>(os, t); return os; }
template<int n, class...T> typename enable_if<(n>=sizeof...(T))>::type _it(istream&, tuple<T...>&){}
template<int n, class...T> typename enable_if<(n< sizeof...(T))>::type _it(istream& is, tuple<T...>& t){ is >> get<n>(t); _it<n+1>(is, t); }
template<class...T> istream& operator>>(istream& is, tuple<T...>& t){ _it<0>(is, t); return is; }
template<class T> istream& operator>>(istream& is, vector<T>& v){ rep(i,v.size()) is >> v[i]; return is; }
template<class T> ostream& operator<<(ostream& os, vector<T> const& v){ rep(i,v.size()) os << v[i] << (i+1==(int)v.size()?"":" "); return os; }
#ifdef DEBUG
#define dump(...) (cerr<<#__VA_ARGS__<<" = "<<mt(__VA_ARGS__)<<" ["<<__LINE__<<"]"<<endl)
#else
#define dump(...)
#endif

vi sieve_of_eratosthenes(int n) {
    vi primes(n+1);
    loop(i,2,n+1) primes[i] = i;
    for (int i = 2; i*i <= n; ++i)
        if (primes[i])
            for (int j = i*i; j <= n; j+=i)
                primes[j] = 0;
    primes.erase(remove(all(primes),0), primes.end());
    return primes;
}

int main(){
    int K,N;
    while(cin>>K>>N){
        vi ps = sieve_of_eratosthenes(N);
        ps.erase(remove_if(all(ps),[&](int x){ return x < K; }), ps.end());
        vi hs(ps.size());
        rep(i,hs.size()){
            int h = ps[i];
            while(h>=10){
                int nh = h;
                h = 0;
                while(nh){
                    h += nh%10;
                    nh/=10;
                }
            }
            hs[i] = h;
        }
        int ans = 0;
        int idx = 0;
        int l=0, r=1;
        set<int> s;
        while(l<hs.size()){
            s.insert(hs[l]);
            while(r<hs.size() && !s.count(hs[r])){
                s.insert(hs[r]);
                r++;
            }
            if(r-l > ans){
                ans = r-l;
                idx = l;
            }
            s.erase(hs[l]);
            l++;
        }
        cout << ps[idx] << endl;
    }
}