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