#coding: utf-8
##yuki_39
import sys

def list_comp(ls1,ls2):
 for i in xrange(len(ls1)):
  if ls1[i]!=ls2[i]:
   break
 return i

s=raw_input()
ls=list(s)
if ls.count(ls[0])==len(ls):
 print "".join(ls)
 sys.exit()

ls_norm=ls[:]
ls_norm.sort()
ls_rev=ls[:]
ls_rev.sort()
ls_rev.reverse()

i=list_comp(ls,ls_rev)
if i==0:
 x=ls_norm[-1]
else:
 x=ls_rev[i]

temp1=ls[i]
ls[i]=x
for j in xrange(len(ls)-1,-1,-1):
 if ls[j]==x:
  ls[j]=temp1
  break

print "".join(ls)