#include <bits/stdc++.h>
using namespace std;
int main() {
  int n, m;
  while (cin >> n >> m) {
    if (n - m > 1) {
      cout << -1 << endl;
    } else if (m > (n + 1) * 2) {
      cout << -1 << endl;
    } else {
      while (n && m) {
        if (n > m) {
          cout << "01";
          n--;
          m--;
        } else if (m - n > 1) {
          cout << "110";
          n--;
          m -= 2;
        } else {
          cout << "10";
          n--;
          m--;
        }
      }
      if (n) cout << 0;
      if (m == 1)
        cout << 1;
      else if (m == 2)
        cout << 11;
      cout << endl;
    }
  }
}
