def manacher(S):
    T = []
    for s in S:
        T += [s, chr(1)]
    T.pop()
    
    n = len(T)
    L = [0] * n
    i = j = 0
    
    while i < n:
        while i >= j and i + j < n and T[i - j] == T[i + j]:
            j += 1
        L[i] = j
        k = 1
        while k + L[i - k] < j and k <= i and i + k < n:
            L[i + k] = L[i - k]
            k += 1
        i += k
        j -= k
    
    for i, l in enumerate(L):
        l = 2 * l - 1
        if i % 2 == 0:
            L[i] = 2 * (l // 4) + 1
        else:
            l += 1
            L[i] = 2 * (l // 4)
            
    return L

    
n, k = map(int, input().split())
if n <= 15:
    for bit in range(1 << n):
        S = bin(bit)[2:].zfill(n)
        x = max(manacher(S))
        if k == x:
            print(S)
            exit()
    print(-1)
    exit()
    
if k <= 3:
    print(-1)
    exit()

S = ["0"] * k
T = "101100"
p = 0
while len(S) < n:
    S.append(T[p])
    p += 1
    if p == 6:
        p = 0
print(*S, sep="")

assert max(manacher(S)) == k