#include <bits/stdc++.h>
using namespace std;
const int N = 100100;
const double pi = 3.141592653589793238462643383279502884197169399375105;
set<int> st;
vector<pair<int, int>> vp;
map<char, long long> mpx;
map<long long, string> mpy;
int farr[N];
vector<int> v;
vector<int> v1;
vector<int> v2;
vector<int> v3;
priority_queue<int> pq;
int main() {
  long long n, t;
  string str = "";
  cin >> n >> t;
  if (t == 10) {
    if (n == 1) {
      cout << -1;
    } else {
      n--;
      while (n--) {
        str += '1';
      }
      str += '0';
      cout << str << endl;
    }
  } else {
    string tt = to_string(t);
    while (n--) str += tt;
    cout << str << endl;
  }
  return 0;
}
