#include <bits/stdc++.h>
using namespace std;
int n, m;
string ans;
int main() {
  cin >> n >> m;
  if (n == m + 1) {
    for (int i = 0; i < m; i++) cout << "01";
    return cout << 0, 0;
  }
  if (n > m || m > 2 * n + 2) return cout << -1, 0;
  while (n) {
    if (m > n)
      ans += "110", m -= 2, n--;
    else
      ans += "10", --m, --n;
  }
  while (m--) ans += '1';
  cout << ans;
}
