#include <bits/stdc++.h>
using namespace std;
int main() {
  int zero, one;
  cin >> zero >> one;
  if (one < zero - 1 || one > 2 * (zero + 1)) {
    cout << -1 << "\n";
    return 0;
  }
  if (one == zero - 1) {
    cout << 0;
    while (one--) {
      cout << 10;
    }
    cout << endl;
    return 0;
  } else {
    int t = 0;
    t = one - zero;
    while (zero--) {
      if (t > 0 && one) {
        cout << 1;
        t--;
        one--;
      }
      if (one) {
        cout << 1;
        one--;
      }
      cout << 0;
    }
    if (one) {
      cout << 1;
      one--;
    }
    if (one) {
      cout << 1;
    }
    cout << endl;
    return 0;
  }
}
