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


/* macro */
#define rep(i,a,b) for(int i=a;i<b;i++)
#define revrep(i,a,b) for(int i = a; i > b; i--)
#define int long long
#define exist(s,e) ((s).find(e)!=(s).end())
#define all(v) (v).begin(), (v).end()
#define each(s,itr) for(auto (itr) = s.begin(); (itr) != s.end(); (itr)++)
#define sum(v) accumulate(all(v), (0LL))
#define pb push_back


/* alias */
template<class T> using vec = vector<T>;
typedef vector<int> vi;
typedef pair<int, int> pi;


/* constant */
const int inf = pow(2, 62);
const int mod = 1e9 + 7;
int dx[8]={1,0,-1,0,-1,1,-1,1};
int dy[8]={0,1,0,-1,-1,-1,1,1};
const string alpha = "abcdefghijklmnopqrstuvwxyz";

/* io_method */
int input(){int tmp;cin >> tmp;return tmp;}
string raw_input(){string tmp;cin >> tmp;return tmp;}
string readline(){string s;getline(cin, s);return s;}
template<class T> void printx(T n){cout << n;}
template<class T, class U> void printx(pair<T, U> p){cout << "(" << p.first << "," << p.second << ")";}
template<class T> void printx(vector<T> v){cout << "{";rep(i,0,v.size()){printx(v[i]);if(i != v.size()-1)printx(",");}cout << "}";}
template<class T> void print(T n){printx(n);cout << endl;}
template<class T> void print(set<T> s){cout << "{";each(s, e){if(e != s.begin()) printx(",");printx(*e);}cout << "}" << endl;}
template<class T, class U> void print(map<T, U> mp){cout << "{";each(mp, e){cout << "(" << e -> first << "," << e -> second << ")";}cout << "}" << endl;}


/* general_method */
template<class T>bool chmax(T &a, const T &b) { if (a<b) { a=b; return 1; } return 0; }
template<class T>bool chmin(T &a, const T &b) { if (b<a) { a=b; return 1; } return 0; }




/* main */

vector<int> eratothenes(int n){

    vector<int> ret;

    vector<bool> isprime(n + 1, true);

    for(int i = 2; i < sqrt(n + 1) + 1; i++){
        if(isprime[i]){
            for(int j = 2; i * j < n + 1; j++){
                isprime[i * j] = false;
            }
        }
    }


    for(int i = 2; i < n + 1; i++){
        if(isprime[i]) ret.push_back(i);
    }

    return ret;

}

int haash(int n){
    
    if(n < 10) return n;

    int ret = 0;

    while(n){
        ret += n % 10;
        n /= 10;
    }

    return haash(ret);
}


signed main(){

    cin.tie(0);
    ios::sync_with_stdio(false);

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

    vi primes = eratothenes(n);

    auto ptr = lower_bound(all(primes), k);

    vi sec_prime;

    while(ptr != primes.end()){
        sec_prime.push_back(*ptr);
        ptr++;
    }

    vi hashed;

    rep(i,0,sec_prime.size()){
        hashed.push_back(haash(sec_prime[i]));
    }

    int ansprime = *hashed.begin();
    int mxlen = 1;

    set<int> used; used.insert(ansprime);

    int l = 0;
    int r = 0;

    while(r < hashed.size()){
        

        if(not exist(used, hashed[r + 1])){
            used.insert(hashed[r + 1]);
            r++;
        }else{
            while(exist(used, hashed[r + 1])){
                used.erase(hashed[l]);
                l++;
            }
        }
    
        if(r - l + 1 >= mxlen){
            mxlen = r - l + 1;
            ansprime = sec_prime[l];
        }


    }

    print(ansprime);

    
    




    



    





    


    

}