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