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