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