#include <bits/stdc++.h>
using namespace std;
int main() {
  int zero, one;
  cin >> zero >> one;
  bool possible = true;
  if (zero > one + 1) possible = false;
  if (one > 2 * zero + 2) possible = false;
  if (!possible)
    cout << "-1\n";
  else {
    string res = "";
    while (one && zero) {
      if (one == zero || zero > one || one - zero == 1) {
        res += "10";
        one--, zero--;
      } else {
        res += "110";
        one -= 2, zero--;
      }
    }
    if (zero)
      res = "0" + res;
    else if (one) {
      if (one == 1)
        res += "1";
      else
        res += "11";
    }
    cout << res << "\n";
  }
  return 0;
}
