---

s = []
n, x = map(int, input().split())

for i in range(n):
    r = ""
    ans = []

    digit = str(i)
    for j in range(len(str(n)) - 1):
        ans.append(int(digit[j]) * int(digit[j + 1]))

    d = sorted(ans)

    for p in d:
        r += str(p)

    if len(r) == x:
        s.append(r)

print(min(s))