#include <bits/stdc++.h>
using namespace std;
const int maxn = 1e5 + 50;
int main() {
  std::ios::sync_with_stdio(false);
  int n, m;
  cin >> n >> m;
  if (m > 2 * n + 2 || m < n - 1)
    cout << -1 << endl;
  else {
    int ok = 0;
    if (m < n) {
      for (int i = 0; i < n; i++) {
        if (i)
          cout << 10;
        else
          cout << 0;
      }
      return 0;
    }
    if (m > n) ok = 1, m -= n;
    for (int i = 0; i < n; i++) {
      if (m) {
        cout << 1;
        m--;
      }
      if (ok)
        cout << 10;
      else
        cout << 0;
    }
    while (m) {
      cout << 1;
      m--;
    }
  }
  return 0;
}
