#include <bits/stdc++.h>
using namespace std;
int n, m, i;
int main() {
  ios_base::sync_with_stdio(false);
  cin >> n >> m;
  if (m < n - 1 || n < ceil(m / 2.0) - 1) {
    cout << -1 << '\n';
    return 0;
  }
  string result;
  for (i = 0; i < n; ++i) {
    result += '0';
    if (m > 0) result += '1';
    m = m - 1;
  }
  for (i = 0; i < result.size(); ++i) {
    if (result[i] == '1' && m > 0) {
      result[i] = '2';
      m = m - 1;
    }
  }
  if (m == 1)
    result.insert(0, "1");
  else if (m == 2)
    result.insert(0, "11");
  for (i = 0; i < result.size(); ++i) {
    if (result[i] == '0' || result[i] == '1') cout << result[i];
    if (result[i] == '2') cout << "11";
  }
  cout << '\n';
  return 0;
}
