import sys
input=lambda:sys.stdin.readline().rstrip()
def isPal(S):
	return S==S[::-1]
def lps(S):
	N=len(S)
	for j in range(N,0,-1):
		for k in range(N-j+1):
			if isPal(S[k:k+j]):
				return j
N,K=map(int,input().split())
if N<9:
	for i in range(pow(2,N)):
		S=format(i,'0'+str(N)+'b')
		if lps(S)==K:
			print(S)
			sys.exit()
	print(-1)
elif K>3:
	print(('1'*K+'010011'*N)[:N])
else:
	print(-1)