#include <bits/stdc++.h>
int main() {
  int n, m, j, i, k, t, min, max;
  while (scanf("%d%d", &n, &m) != EOF) {
    min = m / 2;
    if (m % 2) min++;
    min--;
    max = m + 1;
    if (n > max || n < min) {
      printf("-1\n");
    } else {
      if (n == m + 1) {
        printf("0");
        for (i = 1; i <= (n + m - 1) / 2; i++) printf("10");
        printf("\n");
      } else {
        int x = m - n;
        if (x > m / 2) x = m / 2;
        if (x > n) x = n;
        for (i = 1; i <= x; i++) printf("110");
        k = m - 2 * x;
        t = n - x;
        for (i = 1; i <= k && i <= t; i++) printf("10");
        if (k - t == 1)
          printf("1");
        else if (k - t == 2)
          printf("11");
        printf("\n");
      }
    }
  }
}
