#include <bits/stdc++.h>
using namespace std;
#define FOR(i,a,b) for(int i=(a);i<(b);++i)
#define REP(i,n) FOR(i,0,n)
#define ALL(v) begin(v),end(v)
template<typename A, typename B> inline bool chmax(A & a, const B & b) { if (a < b) { a = b; return true; } return false; }
template<typename A, typename B> inline bool chmin(A & a, const B & b) { if (a > b) { a = b; return true; } return false; }
using ll = long long;
using pii = pair<int, int>;
constexpr ll INF = 1ll<<30;
constexpr ll longINF = 1ll<<60;
constexpr ll MOD = 1000000007;
constexpr bool debug = false;
//---------------------------------//

int main() {
	int N, K;
	cin >> N >> K;
	
	if (N <= 8) {
		REP(i, 1 << N) {
			int cur = 1;
			REP(j, N) {
				FOR(k, 1, N) {
					int l = j - k, r = j + k;
					if (l < 0 || r >= N) break;
					if ((i >> l & 1) == (i >> r & 1)) chmax(cur, k * 2 + 1);
					else break;
				}
				FOR(k, 0, N) {
					int l = j - k, r = j + k + 1;
					if (l < 0 || r >= N) break;
					if ((i >> l & 1) == (i >> r & 1)) chmax(cur, (k + 1) * 2);
					else break;
				}
			}
			if (cur == K) {
				REP(j, N) putchar(i >> j & 1 ? '1' : '0');
				puts("");
				return 0;
			}
		}
		puts("-1");
	}
	else {
		if (K < 4) puts("-1");
		else {
			string ans(K, '0');
			if (ans.size() < N) ans += '1';
			if (ans.size() < N) ans += '0';
			const string s = "110010110010";
			const int dif = N - ans.size();
			REP(i, dif) ans += s[i % s.size()];
			cout << ans << endl;
		}
	}
}