import collections
N = list(input())
ans = 0
dd = collections.defaultdict(lambda:0)
def func(ls):
    if len(ls) < 3:
        dd[''.join(ls)] = 0
        return 0
    s = ''.join(ls)
    if s in dd:
        return dd[s]
    c = len(ls)
    val = 0
    for i in range(c-2):
        for j in range(i+1,c-1):
            for k in range(j+1,c):
                ls0 = ls[:]
                a0,b0,c0 = ls0[i],ls0[k],ls0[j]
                del ls0[i]
                del ls0[j-1]
                del ls0[k-2]
                if a0!=b0 and b0==c0:
                    val = max(val,func(ls0)+int(a0+b0+c0))
                else:
                    val = max(val,func(ls0))
    dd[s] = val
    return val
print(func(N))