def f(S):
    N=len(S)
    X=set()
    for i in range(N):
        for j in range(i+1,N+1):
            T=S[i:j]
            if T==T[::-1]:
                X.add(len(T))
    return max(X)

from itertools import product
N,K=map(int,input().split())

if N<=10:
    for t in product(["0","1"],repeat=N):
        S=""
        for s in t:
            S+=s
        if f(S)==K:
            print(S)
            exit()
    print(-1)
else:
    if K<=3:
        print(-1)
        exit()

    S="1"*K+"010011"*N
    S=S[:N]
    print(S)