import sys
import re

lines = []
for line in sys.stdin:
    lines.append(line)
pos_int = r"[1-9]\d*"
assert len(lines) == 1
assert re.fullmatch(fr"{pos_int} {pos_int}\n", lines[0])
N, K = map(int, lines[0].split())
assert 1 <= K <= N <= 1000

if 2 * K >= N:
    S = "0" * K + "1" * (N - K)
elif N <= 8 and K == 3:
    S = "00010" + "1" * (N - 5)
elif N >= 9 and K >= 4:
    S = "1" * K
    T = "001011"
    for i in range(N - K):
        S += T[i % len(T)]
else:
    S = "-1"
print(S)