#include <bits/stdc++.h>
using namespace std;
int main() {
  int n, m;
  cin >> n >> m;
  if (n > m + 1 || m > (2 * n + 2)) {
    cout << "-1\n";
    return 0;
  }
  if (n >= m) {
    string s;
    for (int i = 0; i < n + m; i++) {
      if (i % 2 == 0)
        s += '0';
      else
        s += '1';
    }
    cout << s << "\n";
    return 0;
  }
  string s;
  for (int i = 0; i < min(n, m - n - 1); i++) {
    s += "110";
  }
  if (m == 2 * n + 2) {
    s += "11";
    cout << s << "\n";
    return 0;
  }
  for (int i = 0; i < 2 * n + 1 - m; i++) s += "10";
  s += '1';
  cout << s << "\n";
}
