import strutils, sequtils, algorithm, math

var
  n = readLine(stdin).parseInt()
  nStr = n.intToStr()
  nStrTmp: string
  maxV = n

for i in countup(0, nStr.len() - 2):
  for j in countup(1, nStr.len() - 1):
    nStrTmp = nStr
    nStrTmp[i] = nStr[j]
    nStrTmp[j] = nStr[i]
    maxV = max(maxV, nStrTmp.parseInt)

echo(maxV)