#include <bits/stdc++.h>
using namespace std;
int a, b;
int main() {
  cin >> a >> b;
  if (a > b + 1 or (a + 1) * 2 < b) {
    cout << -1;
    return 0;
  }
  string s;
  s.push_back('1');
  int n = a + b, ok = 1;
  for (int i = 1; i < n; i++) {
    if (ok and b > a) {
      s.push_back('1');
      ok = 0;
      b--;
    } else {
      if (s[i - 1] == '0') {
        ok = 1;
        s.push_back('1');
        b--;
      } else {
        s.push_back('0');
        a--;
      }
    }
  }
  if (a == 1) s.pop_back(), s = "0" + s;
  cout << s;
}
