#include <bits/stdc++.h>
#pragma GCC optimize("Ofast")
#pragma GCC target("avx,avx2,fma")
#pragma GCC optimization("unroll-loops")
using namespace std;
long long dx[] = {1, 0, -1, 0};
long long dy[] = {0, 1, 0, -1};
void debug_out(vector<string> __attribute__((unused)) args,
               __attribute__((unused)) long long idx,
               __attribute__((unused)) long long LINE_NUM) {
  cerr << "\n";
}
template <typename Head, typename... Tail>
void debug_out(vector<string> args, long long idx, long long LINE_NUM, Head H,
               Tail... T) {
  if (idx > 0)
    cerr << ", ";
  else
    cerr << "Line(" << LINE_NUM << ") ";
  stringstream ss;
  ss << H;
  cerr << args[idx] << " = " << ss.str();
  debug_out(args, idx + 1, LINE_NUM, T...);
}
string solve() {
  long long n, m;
  cin >> n >> m;
  string ans;
  if (n == m) {
    for (long long i = 0; i < n; i++) {
      ans.push_back('1');
      ans.push_back('0');
    }
    return ans;
  }
  if (n > m) {
    if (n - m > 1) return "-1";
  } else {
    if (n == 1 && m > 4)
      return "-1";
    else if (m > 4 + 2 * (n - 1))
      return "-1";
  }
  if (n > m) {
    string ans;
    for (long long i = 0; i < m; i++) {
      ans.push_back('0');
      ans.push_back('1');
    }
    ans.push_back('0');
    return ans;
  } else {
    if (n == 1) {
      string ans;
      if (m == 4) {
        ans += "11";
        ans.push_back('0');
        ans += "11";
        return ans;
      }
      if (m == 3) {
        ans += "11";
        ans.push_back('0');
        ans.push_back('1');
        return ans;
      }
      if (m == 2) {
        ans += "11";
        ans.push_back('0');
        return ans;
      } else {
        ans += "10";
        return ans;
      }
    } else {
      string ans;
      if (m == 4 + 2 * (n - 1)) {
        for (long long i = 0; i < n; i++) {
          ans += "11";
          ans.push_back('0');
        }
        ans += "11";
        return ans;
      }
      while (m != n + 1) {
        ans += "11";
        ans.push_back('0');
        m -= 2, n -= 1;
      }
      for (long long i = 0; i < n; i++) ans.push_back('1'), ans.push_back('0');
      ans.push_back('1');
      return ans;
    }
  }
}
signed main() {
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);
  cout << solve();
  return 0;
}
