#include <bits/stdc++.h>
using namespace std;
struct ar {
  int a;
  int b;
};
bool sortbya(ar l, ar r) { return (l.a < r.a); }
int main() {
  int n, t;
  cin >> n >> t;
  int a[n];
  for (int i = 0; i < n; i++) a[i] = 0;
  if (n == 1 && t < 10) {
    cout << t;
    return 0;
  } else if (n == 1 && t == 10) {
    cout << -1;
    return 0;
  }
  if (t != 10)
    a[0] = t;
  else
    a[0] = 1;
  for (int i = 0; i < n; i++) cout << a[i];
  return 0;
}
