#include <bits/stdc++.h>
#pragma GCC optimize "trapv"
using namespace std;
const long long MOD = 1e9 + 7;
void print() { cout << "\n"; }
void printArray() { return; }
void read() { return; }
template <typename T, typename... Args>
void print(T a, Args... arg) {
  cout << a << " ";
  print(arg...);
}
template <typename T, typename... Args>
void read(T &a, Args &...arg) {
  cin >> a;
  read(arg...);
}
template <typename T, typename... Args>
void read(vector<T> &v, Args &...arg) {
  for (auto &i : v) cin >> i;
  read(arg...);
}
template <typename T, typename... Args>
void printArray(vector<T> &v, Args &...arg) {
  for (auto i : v) cout << i << " ";
  cout << "\n";
  printArray(arg...);
}
long long power(long long a, long long b) {
  long long res = 1;
  while (b) {
    if (b & 1LL) res = res * a;
    b >>= 1LL;
    a = a * a;
  }
  return res;
}
long long modPower(long long a, long long b) {
  long long res = 1;
  while (b) {
    if (b & 1L) res = (res % MOD * a % MOD) % MOD;
    b >>= 1;
    a = (a % MOD * a % MOD) % MOD;
  }
  return res;
}
long long gcdExtended(long long a, long long b, long long *x, long long *y) {
  if (a == 0) {
    *x = 0, *y = 1;
    return b;
  }
  long long x1, y1;
  long long gcd = gcdExtended(b % a, a, &x1, &y1);
  *x = y1 - (b / a) * x1;
  *y = x1;
  return gcd;
}
long long modInverse(long long b, long long m) {
  long long x, y;
  long long g = gcdExtended(b, m, &x, &y);
  if (g != 1) return -1;
  return (x % m + m) % m;
}
long long modDivide(long long a, long long b, long long m = MOD) {
  a = a % m;
  long long inv = modInverse(b, m);
  if (inv == -1)
    return -1;
  else
    return (inv * a) % m;
}
void runCase_() {
  long long n, m;
  read(n, m);
  if (m < n - 1 || m > 2 * (n + 1)) {
    print(-1);
    return;
  } else {
    string ans = "";
    while (n > 0) {
      ans += '0';
      if (m > 0) ans += '1';
      --n, --m;
      if (m > n - 1 && m > 0) {
        ans += '1';
        --m;
      }
    }
    if (m == 1) ans = '1' + ans;
    if (m == 2) ans = "11" + ans;
    if (m == 3) ans = "11" + ans + '1';
    if (m == 4) ans = "11" + ans + "11";
    print(ans);
  }
}
signed main() {
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);
  runCase_();
  return 0;
}
