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