#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 main() {
	int n, k;
	cin >> n >> k;
	if ((n + k - 1) / k <= 2) {
		for (int i = 0; i < k; i++) {
			cout << 0;
		}
		for (int i = 0; i < n - k; i++) {
			cout << 1;
		}
		cout << endl;
	}
	else {
		cout << -1 << endl;
	}
}