s=input();l=len(s);r=range
def f(u,c):
 m=c
 for i in r(l):
  for j in r(i+1,l):
   for k in r(j+1,l):
    if s[i]!='0'and s[j]==s[k]and s[i]!=s[j]and not(u[i]+u[j]+u[k]):u[i]=u[j]=u[k]=1;m=max(m,f(u,c+int(s[i]+s[j]+s[k])));u[i]=u[j]=u[k]=0
 return m
u=[0]*l
print(f(u,0))