#include <bits/stdc++.h>
using namespace std;
map<long long int, long long int> mp, mk;
set<long long int> s1, s2;
vector<long long int> v, w;
string s = "", p = "", q = "";
char ch;
long long int m, n, c, i, j, k, l, r, x, t, y, u, e, f, g, h, mn, mx, d, z;
int main() {
  cin >> n >> t;
  if (t == 10) {
    if (n == 1) {
      cout << -1;
      return 0;
    } else {
      cout << 1;
      for (i = 1; i < n; i++) cout << 0;
      return 0;
    }
  }
  for (i = 1; i <= n; i++) cout << t;
}
