#include <bits/stdc++.h>
using namespace std;
int32_t main() {
  long long n, t, count = 0;
  cin >> n >> t;
  if (n == 1 && t == 10) {
    cout << "-1";
  } else if (n >= 2 && t == 10) {
    for (long long i = 1; i < n; i++) {
      cout << "1";
    }
    cout << "0";
  } else {
    while (n--) {
      cout << t;
    }
  }
  return 0;
}
