#include <bits/stdc++.h>
using namespace std;
int main() {
  int x, y;
  cin >> x >> y;
  string ans;
  if (x > y + 1 || y > 2 * (x + 1)) {
    cout << -1 << endl;
  } else if (x == y + 1 || x == y) {
    for (int i = 0; i < x + y; i++) {
      if (i & 1) {
        ans.push_back('1');
      } else {
        ans.push_back('0');
      }
    }
    cout << ans << endl;
  } else {
    int count = y;
    y = x + 1;
    count -= y;
    for (int i = 0; i < x + y; i++) {
      if (i & 1) {
        ans.push_back('0');
      } else {
        ans.push_back('1');
      }
    }
    string result;
    for (int i = 0; i < ans.length(); i++) {
      result.push_back(ans[i]);
      if (ans[i] == '1' && count > 0) {
        result.push_back('1');
        count--;
      }
    }
    cout << result << endl;
  }
  return 0;
}
