import random

def test():
    res = [1,0,1,0,1]
    while True:
        ok = [True,True]
        n = len(res)
        if res[n-1]==res[n-4] and res[n-2]==res[n-3]:
            ok[res[n-5]] = False
        if n>=6 and res[n-1]==res[n-5] and res[n-2]==res[n-4]:
            ok[res[n-6]] = False
        if all(res[i]==1 for i in range(n-4,n)) and res[n-5]==0:
            ok[1] = False
        if all(res[i]==0 for i in range(n-4,n)) and res[n-5]==1:
            ok[0] = False
        if ok[0]:
            if not ok[1]:
                res.append(0)
            else:
                res.append(random.randint(0,99)%2)
        elif ok[1]:
            res.append(1)
        else:
            break
    return res

def test_p(N):
    res = [1,0,1,0]
    while True:
        res += [0,0,1,1,0,1]
        for n in range(len(res),len(res)-6,-1):
            for j in range(2):
                if res[n-j-1]!=res[n-5+j]:
                    break
            else:
                assert False
            for j in range(2):
                if res[n-j-1]!=res[n-6+j]:
                    break
            else:
                assert False

        if len(res) > 100:
            break
    return res

def test_3():
    res = [1,0,1]
    while True:
        ok = [True,True]
        n = len(res)
        if res[n-1]==res[n-2]:
            ok[res[n-3]] = False
        if n>=4 and res[n-1]==res[n-3]:
            ok[res[n-4]] = False
        if ok[0]:
            if not ok[1]:
                res.append(0)
            else:
                res.append(random.randint(0,99)%2)
        elif ok[1]:
            res.append(1)
        else:
            break
    return res

M = 0
case = 0
s = ""
while case:
    r = test_p(4)
    if len(r) > M:
        M = len(r)
        s = r
    #M = max(M,len(r))
    case -= 1

#print(M)
#print(s)

N,K = map(int,input().split())
assert K%2
if K%2==1:
    if K==1:
        if N==1:
            print(1)
        else:
            print(-1)
    elif K==3:
        if N<=8:
            s = [0,0,0,1,0,1,1,1]
            s = s[:N]
            for i in range(N):
                s[i] = str(s[i])
            print("".join(s))
        else:
            print(-1)
    else:
        s = [1-(i%2) for i in range(K)]
        s += [0,0,1,1,0,1] * (N//5 + 1)
        s = s[:N]
        for i in range(N):
            s[i] = str(s[i])
        print("".join(s))