#include <bits/stdc++.h>
using namespace std;
int main() {
  int n, m, i, lo, hi, count;
  cin >> n >> m;
  lo = (m - 1) / 2;
  hi = m + 1;
  if (n < lo || n > hi) {
    printf("-1");
    return 0;
  }
  if (n == hi) {
    printf("0");
    n--;
  }
  int target = n + m;
  count = 0;
  while (count < target) {
    if (n == m) {
      printf("10");
      n--;
      m--;
      count += 2;
    } else {
      if (n >= 1 && m >= 2) {
        printf("110");
        m -= 2;
        n--;
        count += 3;
      } else if (n == 0 && m >= 2) {
        printf("11");
        m -= 2;
        count += 2;
      } else if (n == 0 && m == 1) {
        printf("1");
        m--;
        count++;
      }
    }
  }
  return 0;
}
