// includes
#include <bits/stdc++.h>
using namespace std;

// macros
#define pb emplace_back
#define mk make_pair
#define FOR(i, a, b) for(int i=(a);i<(b);++i)
#define rep(i, n) FOR(i, 0, n)
#define rrep(i, n) for(int i=((int)(n)-1);i>=0;i--)
#define irep(itr, st) for(auto itr = (st).begin(); itr != (st).end(); ++itr)
#define irrep(itr, st) for(auto itr = (st).rbegin(); itr != (st).rend(); ++itr)
#define all(x) (x).begin(),(x).end()
#define sz(x) ((int)(x).size())
#define UNIQUE(v) v.erase(unique(v.begin(), v.end()), v.end())
#define bit(n) (1LL<<(n))
// functions
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(a > b){a = b; return 1;} return 0;}
template <typename T> istream &operator>>(istream &is, vector<T> &vec){for(auto &v: vec)is >> v; return is;}
template <typename T> ostream &operator<<(ostream &os, const vector<T>& vec){for(int i = 0; i < vec.size(); i++){ os << vec[i]; if(i + 1 != vec.size())os << " ";} return os;}
template <typename T> ostream &operator<<(ostream &os, const set<T>& st){for(auto itr = st.begin(); itr != st.end(); ++itr){ os << *itr; auto titr = itr; if(++titr != st.end())os << " ";} return os;}
template <typename T> ostream &operator<<(ostream &os, const unordered_set<T>& st){for(auto itr = st.begin(); itr != st.end(); ++itr){ os << *itr; auto titr = itr; if(++titr != st.end())os << " ";} return os;}
template <typename T> ostream &operator<<(ostream &os, const multiset<T>& st){for(auto itr = st.begin(); itr != st.end(); ++itr){ os << *itr; auto titr = itr; if(++titr != st.end())os << " ";} return os;}
template <typename T> ostream &operator<<(ostream &os, const unordered_multiset<T>& st){for(auto itr = st.begin(); itr != st.end(); ++itr){ os << *itr; auto titr = itr; if(++titr != st.end())os << " ";} return os;}
template <typename T1, typename T2> ostream &operator<<(ostream &os, const pair<T1, T2> &p){os << p.first << " " << p.second; return os;}
template <typename T1, typename T2> ostream &operator<<(ostream &os, const map<T1, T2> &mp){for(auto itr = mp.begin(); itr != mp.end(); ++itr){ os << itr->first << ":" << itr->second; auto titr = itr; if(++titr != mp.end())os << " "; } return os;}
template <typename T1, typename T2> ostream &operator<<(ostream &os, const unordered_map<T1, T2> &mp){for(auto itr = mp.begin(); itr != mp.end(); ++itr){ os << itr->first << ":" << itr->second; auto titr = itr; if(++titr != mp.end())os << " "; } return os;}
//  types
using ll = long long int;
using P = pair<int, int>;
// constants
const int inf = 1e9;
const ll linf = 1LL << 50;
const double EPS = 1e-10;
const int mod = 1000000007;
const int dx[4] = {-1, 0, 1, 0};
const int dy[4] = {0, -1, 0, 1};
// io
struct fast_io{
  fast_io(){ios_base::sync_with_stdio(false); cin.tie(0); cout << fixed << setprecision(20);}
} fast_io_;

template <typename T>
T power(T a, T n, T mod) {
  T res = 1;
  T tmp = n;
  T curr = a;
  while(tmp){
    if(tmp % 2 == 1){
      res = (T)(res * curr % mod);
    }
    curr = (T)(curr * curr % mod);
    tmp >>= 1;
  }

  return res;
}

template <typename T>
bool suspect(T a, int s, T d, T n){
  T x = power<T>(a, d, n);
  if(x == 1)return true;
  for(int r = 0; r < s; r++){
    if(x == n - 1)return true;
    x = x * x % n;
  }
  return false;
}

template <typename T>
bool millar_rabin(T n){
  if(n <= 1 || (n > 2 && n % 2 == 0))return false;
  vector<ll> test = {2, 3, 5, 7, 11, 13, 17, 19, 23};
  T d = n - 1;
  int s = 0;
  while(d % 2 == 0)s++, d /= 2;
  for(int i = 0; i < test.size() && test[i] < n; i++){
    if(!suspect<T>(test[i], s, d, n))return false;
  }
  return true;
}

ostream& operator<<(ostream& dest, __int128_t value) {
  ostream::sentry s(dest);
  if(s){
    __uint128_t tmp = value < 0 ? - value: value;
    char buf[128];
    char *d = end(buf);
    do{
      --d;
      *d = "0123456789"[tmp % 10];
      tmp /= 10;
    }while(tmp != 0);
    if(value < 0)--d, *d='-';
    int len = end(buf) - d;
    if(dest.rdbuf()->sputn(d, len) != len){
      dest.setstate(ios_base::badbit);
    }
  }
  return dest;
}

__int128_t to_int128(string s){
  __int128_t res = 0;
  for(size_t i = 0; i < s.size(); i++){
    res = res * 10 + (s[i] - '0');
  }
  return res;
}


int n, c;

__int128_t res = -1;
string v = "";

void dfs(){
  if(sz(v) == n){
    string t = v; reverse(all(t));
    string u = v + char('0' + c) + t;
    __int128_t val = to_int128(u);
    if(millar_rabin<__int128_t>(val)){
      res = max(res, val);
    }
    return;
  }
  for(char i = '0'; i <= '9'; i++){
    if(sz(v) == 0 && i == 0)continue;
    v += i;
    dfs();
    v.pop_back();
  }
}

int main(int argc, char const* argv[])
{
  cin >> n >> c;
  if(c < 0){
    if(n == 1)cout << 11 << endl;
    else{
      rep(i, 2 * n)cout << 9;
      cout << endl;
    }
    return 0;
  }

  dfs();
  if(res == -1){
    rep(i, n)cout << 9;
    cout << c;
    rep(i, n)cout << 9;
    cout << endl;
  }else{
    cout << res << endl;
  }
  return 0;
}



Measured memory_bytes: 3144