from math import gcd
from collections import Counter
def gcds(ls):
  ret = 0
  for i in ls:
    if ret*i == 0:
      ret = max(ret,i)
    else:
      ret = gcd(ret,i)
    print(ret,i)
  return ret
n = input()
c = Counter(n)
d = list(int(i) for i in c.keys())
ans = 1
if len(d) == 1:
  ans = n
else:
  if len(d) == 2 and 0 in d:
    ans *= max(d)
  elif gcds(d) != 1:
    b = gcds(d)
    if b%3:
      ans *= b
    else:
      ans *= b//3
    dsum = 0
    for i,j in c.items():
      dsum += int(i)*j
    if dsum%9 == 0:
      ans *= 9
    elif dsum%3 == 0:
      ans *= 3
print(ans)