n, k = map(int, input().split())

if k == 1:
    if n > 1:
        print(-1)
    else:
        print(0)
elif k == 2:
    if n > 4:
        print(-1)
    else:
        print('0011'[:n])
elif k == 3:
    if n > 8:
        print(-1)
    else:
        print('11101000'[:n])
else:
    d = [k]
    n -= k
    i = 0
    t = [1, 1, 2, 2]
    while n:
        v = min(n, t[i])
        d.append(v)
        n -= v
        i = (i + 1) & 3
    for i, c in enumerate(d):
        if i % 2:
            print('1' * c, end='')
        else:
            print('0' * c, end='')
    print()