def rev(s):
    return s[::-1]

def pad(s, N):
    return "0" * (N - len(s)) + s

def check(s, K):
    N = len(s)
    ma = 0
    for i in range(N):
        for j in range(i, N + 1):
            if s[i:j] == rev(s[i:j]):
                ma = max(ma, j - i)
    if ma == K:
        print(s)
        exit()
    return
                
N, K = map(int, input().split())
if N <= 15:
    for i in range(1 << N):
        s = bin(i)[2:]
        s = pad(s, N)
        check(s, K)
    print(-1)
else:
    if K <= 3:
        print(-1)
    else:
        ans = [1] * K + [0, 0, 1, 0, 1, 1] * N
        print(*ans[:N], sep="")