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