#include <bits/stdc++.h>
using namespace std;
int n, m, n1, m1;
int main() {
  ios::sync_with_stdio(0), cin.tie(0), cout.tie(0);
  cin >> n >> m;
  n1 = n, m1 = m;
  if ((n1 == m1 + 1 and !(n1 + m1 % 2)) or n1 > m1 + 1 or
      m1 / 2 + (m1 % 2) > n1 + 1 or
      (m1 / 2 + (m1 % 2)) == n1 + 1 and !(m1 / 2 + (m1 % 2) + n1 % 2)) {
    cout << -1;
    exit(0);
  }
  int p = 0;
  for (int i = 0; i < n + m; i++) {
    if (n1 > m1 or p == 2)
      cout << 0, p = 0, n1--;
    else
      cout << 1, p++, m1--;
  }
  return 0;
}
