#include <bits/stdc++.h>
using namespace std;
const int N = (int)(2 * 1e5 + 10);
void solve() {
  int nz, no;
  cin >> nz >> no;
  if (nz > no + 1) {
    cout << -1 << endl;
    return;
  }
  if (no > 2 * nz + 2) {
    cout << -1 << endl;
    return;
  }
  if (nz > no) {
    cout << 0;
    nz--;
  }
  while (no > nz) {
    if (nz == 0) {
      while (no) {
        cout << 1;
        no--;
      }
      break;
    }
    cout << 110;
    no -= 2;
    nz -= 1;
  }
  while (no) {
    cout << 10;
    no--;
    nz--;
  }
  return;
}
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);
  cout.tie(NULL);
  long long int t;
  t = 1;
  while (t--) {
    solve();
  }
  return 0;
}
