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