#int(input())
#map(int, input().split())
#list(map(int, input().split()))

def f(x):
    m = 1
    l = len(x)
    for i in range(l-2):
        for j in range(i+2, l+1):
            u = x[i:j]
            # print(u, i, j)
            if u == u[::-1]:
                m = max(m, j-i)

    return m

N, K = map(int, input().split())

if N <= 8:
    ff = 0
    for i in range(1 << N):
        # i = 24
        b = format(i, "0" + str(N) + "b")
        a = f(b)
        if a == K:
            ff = 1
            break

    if ff == 1:
        print(b)
    else:
        print(-1)
else:
    if K <= 3:
        print(-1)
    else:
        s = "1" * K + "010011" * (N // 6 + 1)
        print(s[:N])