#include <bits/stdc++.h>
using namespace std;
int main() {
  int n, m, two, one;
  cin >> n >> m;
  if (m < n - 1 || m > 2 * n + 2)
    cout << "-1";
  else {
    if (m < n) {
      cout << "0";
      n--;
    }
    while (m > 0 || n > 0) {
      two = max(m - n - 1, 0);
      one = min(2 * n + 2, m);
      if (two) {
        cout << "11";
        m -= 2;
        two--;
      } else if (one) {
        cout << "1";
        m--;
        one--;
      }
      if (n) cout << "0";
      n--;
    }
  }
  return 0;
}
