#include <bits/stdc++.h>
using namespace std;
int main() {
  int n, k;
  cin >> n >> k;
  if (k == 10 && n <= 1) {
    cout << -1;
    return 0;
  }
  if (k == 10) {
    cout << k;
    n -= 2;
    for (int i = 1; i <= n; i++) cout << 0;
  } else {
    cout << k;
    n--;
    for (int i = 1; i <= n; i++) cout << 0;
  }
  return 0;
}
