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