def f(s,n):
 r=n
 for i in s:
  for j in s:
   p=s.split(i,1);a=p[0]+p[1].replace(j,'',2)
   if len(s)-len(a)>2and i>'0'and i!=j:r=max(r,f(a,n+int(i+j+j)))
 return r
print(f(input(),0))