#include <iostream>
#include <string>
#include <algorithm>
#include <vector>
#include <iomanip>
#include <cmath>
#include <stdio.h>
#include <queue>
#include <deque>
#include <cstdio>
#include <set>
#include <map>
#include <bitset>
#include <stack>
#include <cctype>
using namespace std;
int longest_palindrome(string text, int n) {
	int rad[100010], i, j, k;
	for (i = 0, j = 0; i < 2 * n; i += k, j = max(j - k, 0)) {
		while (i - j >= 0 && i + j + 1 < 2 * n && text[(i - j) / 2] == text[(i + j + 1) / 2]) ++j;
		rad[i] = j;
		for (k = 1; i - k >= 0 && rad[i] - k >= 0 && rad[i - k] != rad[i] - k; ++k)
			rad[i + k] = min(rad[i - k], rad[i] - k);
	}
	return *max_element(rad, rad + 2 * n); // ret. centre of the longest palindrome
}
int main() {
	int n, k;
	cin >> n >> k;
	if (k < 4) {
		if ((n + k - 1) / k > 2) {
			cout << -1 << endl;
		}
		else {
			for (int i = 0; i < k; i++) {
				cout << 0;
			}
			for (int i = 0; i < n - k; i++) {
				cout << 1;
			}
			cout << endl;
		}
	}
	else {
		for (int i = 0; i < k; i++) {
			cout << 1;
		}
		string s = "";
		for (int i = 0; i < k - 1; i++) {
			if (i != k - 2) {
				s += '0';
			}
			else {
				s += '1';
			}
		}
		for (int i = 0; i < k - 1; i++) {
			if (i != 0) {
				s += '1';
			}
			else {
				s += '0';
			}
		}
		for (int i = 0; i < n - k; i++) {
			cout << s[i % s.size()];
		}
		cout << endl;
	}
}