#include <bits/stdc++.h>
using namespace std;
int main() {
  int n, m, i;
  cin >> n >> m;
  int a[m + n + 5];
  if (n - m > 1) {
    cout << "-1" << endl;
    return 0;
  } else if (m > (2 * n + 2)) {
    cout << "-1" << endl;
    return 0;
  }
  while ((m > 0) && (n > 0)) {
    if (m > n) {
      cout << "110";
      m = m - 2;
      n = n - 1;
    } else if (m == n) {
      while (m != 0) {
        cout << "10";
        m--;
      }
    } else if (n > m) {
      cout << "0";
      n--;
    }
  }
  while (m != 0) {
    cout << "1";
    m--;
  }
  return 0;
}
