import sys
input=lambda: sys.stdin.readline().rstrip()
N=list(input())
k=len(N)
ans=int("".join(N))
for i in range(k-1):
  for j in range(i+1,k):
    cur=0
    for ii in range(k):
      if ii==i:
        cur+=int(N[j])*10**(k-1-ii)
      elif ii==j:
        cur+=int(N[i])*10**(k-1-ii)
      else:
        cur+=int(N[ii])*10**(k-1-ii)
    ans=max(ans,cur)
print(ans)