#include <bits/stdc++.h>
using namespace std;
int main() {
  int n, m, i, l, r, j;
  scanf("%d%d", &n, &m);
  l = n - 1;
  r = 2 * (n + 1);
  if (m < l || m > r) {
    printf("-1\n");
    return 0;
  }
  if (m == l) {
    for (i = 1; i < n; i++) printf("01");
    printf("0\n");
  } else {
    int num = n + 1, temp;
    for (i = 1; i <= n; i++) {
      temp = m / num;
      for (j = 1; j <= temp; j++) printf("1");
      printf("0");
      m -= temp;
      num--;
    }
    for (i = 1; i <= m; i++) printf("1");
    printf("\n");
  }
  return 0;
}
