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