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