#include <bits/stdc++.h>
using namespace std;
list<string> vec;
list<string>::iterator it;
int main() {
  int n, m;
  scanf("%d", &n);
  ;
  scanf("%d", &m);
  ;
  if (((n - 1) * 2 + 4) < m || m < (n - 1)) {
    cout << "-1" << endl;
    return 0;
  }
  if (n == 1 && m == 1) {
    cout << "01" << endl;
    return 0;
  } else if (n == 1 && m == 2) {
    cout << "011" << endl;
    return 0;
  } else if (n == 1 && m == 3) {
    cout << "1011" << endl;
    return 0;
  } else if (n == 1 && m == 4) {
    cout << "11011" << endl;
    return 0;
  } else {
    for (int i = 0; i < n - 1; i++) {
      vec.push_back("0");
      vec.push_back("1");
    }
    vec.push_back("0");
    m -= (n - 1);
    if ((m - 2) >= 0) {
      vec.push_back("11");
      m -= 2;
    }
    if ((m - 2) >= 0) {
      vec.push_front("11");
      m -= 2;
    }
  }
  for (it = vec.begin(); it != vec.end(); ++it) {
    cout << *it;
    if (m > 0 && (*it) == "0") {
      cout << "1";
      m--;
    }
  }
}
