#include <bits/stdc++.h>
using namespace std;
int main() {
  int n, m;
  double x, y;
  cin >> n >> m;
  x = n;
  y = m;
  if (m > (n * 2) + 2 || m + 1 < n) {
    cout << -1;
    return 0;
  }
  if (m == n - 1) {
    cout << 0;
    n--;
  }
  while (m > 0 && n > 0) {
    if (m > n) {
      if (m - 2 >= n) {
        cout << 11 << 0;
        m -= 2;
        n--;
      } else {
        m--;
        n--;
        cout << 1 << 0;
      }
    } else {
      cout << 1 << 0;
      m--;
      n--;
    }
  }
  while (m <= 2 && m != 0) {
    cout << 1;
    m--;
  }
}
