#include <bits/stdc++.h>
using namespace std;
int main() {
  int n, x;
  cin >> n >> x;
  if (x == 10) {
    if (n == 1)
      cout << -1;
    else {
      for (int i = 0; i < n - 1; ++i) {
        cout << 1;
      }
      cout << 0;
    }
  } else if (x != 10) {
    {
      for (int i = 1; i <= n; ++i) cout << x;
    }
  }
  return 0;
}
