import strutils, algorithm

var
  N = stdin.readLine
  arr_N = N.reversed.reversed
  dic = newSeq[int]()

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

let
  p1 = N.rfind dic.max.repr
  p2 = N.find dic.min.repr

swap(arr_N[p1], arr_N[p2])

echo max(arr_N.join.parseInt, N.parseInt)