#include <bits/stdc++.h>
using namespace std;
int main() {
  int n0, n1;
  cin >> n0 >> n1;
  if (n0 > n1 + 1 || 2 * n0 + 2 < n1) {
    cout << -1;
    return 0;
  }
  if (n0 > n1) {
    printf("0");
    n0--;
  }
  while (n0) {
    if (n0 == n1) {
      printf("10");
      n0--;
      n1--;
    } else {
      printf("110");
      n0--;
      n1 -= 2;
    }
  }
  while (n1) {
    printf("1");
    n1--;
  }
  cout << endl;
}
