import strutils, algorithm

let
  N = stdin.readLine
  arr_N = N.reversed.reversed
var
  dic = newSeq[int]()
  arr_N1, arr_N2 = arr_N

for n in N:
  dic.add (n & "").parseInt

swap(arr_N1[0], arr_N1[N.rfind dic.max.repr])
swap(arr_N2[^1], arr_N2[N.find dic.min.repr])


echo max(arr_N1.join.parseInt, arr_N2.join.parseInt)