#include <bits/stdc++.h>
using namespace std;
int main() {
  int n, m;
  cin >> n >> m;
  vector<int> a(n + 1, 0);
  if (!(n - 1 <= m && m <= 2 * (n + 1))) {
    cout << -1;
    exit(0);
  }
  for (int i = 1; i < n; i++) m--, a[i] = 1;
  for (int i = 0; i <= n && m > 0; i++) {
    while (m > 0 && a[i] < 2) a[i]++, m--;
  }
  cout << (a[0] ? string(a[0], '1') : "");
  for (int i = 1; i <= n; i++) cout << '0' << (a[i] ? string(a[i], '1') : "");
}
