N,K=map(int,input().split())
M=N
if K*2>=N:
  print(('0'*K)+('1'*(N-K)))
X=[]
C=0
while K:
  X.append(K)
  if len(X)>1:
    X[-1]-=1
  if len(X)>2:
    X[-2]-=1
    N+=1
  N-=X[-1]
  if N<0:
    X[-1]-=N
  if N<0 or X[-1]<=0:
    break
  C+=1
  if C&1==0:
    K-=1
if sum(X)<M:
  print(-1)
else:
  print(''.join([str(i&1)*X[i] for i in range(len(X))]))