#include <bits/stdc++.h>
using namespace std;
int main() {
  ios::sync_with_stdio(false);
  cin.tie(0);
  int n, m;
  cin >> n >> m;
  if (m % 2 == 0 && m / 2 - 2 >= n)
    cout << -1 << endl;
  else if (m % 2 == 1 && m / 2 - 1 >= n)
    cout << -1 << endl;
  else if (n - 1 > m)
    cout << -1 << endl;
  else if (n > m) {
    while (m && n) {
      cout << "01";
      m--;
      n--;
    }
    cout << 0 << endl;
  } else {
    while (n && m) {
      if (m > n) {
        cout << 110;
        m = m - 2;
        n--;
      } else {
        cout << 10;
        m--;
        n--;
      }
    }
    while (m) {
      cout << 1;
      m--;
    }
    cout << endl;
  }
  return 0;
}
