#include <bits/stdc++.h>
using namespace std;
int main() {
  long long n, m, r = 0, k = 1;
  cin >> n >> m;
  if ((n > m + 1) || (2 * n + 2 < m)) {
    cout << "-1";
    return 0;
  }
  while (n + m > 0) {
    if ((r == 1) || ((n < m) && (k < 3))) {
      cout << 1;
      m--;
      k++;
      r = 0;
    } else {
      cout << 0;
      n--;
      r = 1;
      k = 1;
    }
  }
}
