#include <bits/stdc++.h>
using namespace std;
long long power(int x, unsigned int y) {
  long long res = 1;
  while (y > 0) {
    if (y & 1) res = res * x;
    y >>= 1;
    x *= x;
  }
  return res;
}
void solve() {
  int zero, ones;
  cin >> zero >> ones;
  if (zero < (ceil(double((ones / 2.00))) - 1) ||
      (zero > ones && zero - ones > 1)) {
    cout << -1;
  } else {
    if (zero > ones) {
      while (zero || ones) {
        if (zero) cout << "0", zero--;
        if (ones) cout << "1", ones--;
      }
    } else {
      while (zero || ones) {
        if (zero != ones) {
          if (ones >= 2) {
            cout << "11";
            ones -= 2;
          } else if (ones)
            cout << "1", ones--;
          if (zero) cout << "0", zero--;
        } else {
          if (ones) cout << "1", ones--;
          if (zero) cout << "0", zero--;
        }
      }
    }
  }
}
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);
  solve();
}
