from itertools import combinations

n = input()

def is_cww(i, j, k):
    return i != '0' and i != j and j == k

max_score = 0

stack = [(0, n)]

while len(stack) > 0:
    score, ns = stack[0]
    del stack[0]

    if len(ns) < 3:
        if max_score < score:
            max_score = score
        continue

    num_cww = 0
    for i, j, k in combinations(range(len(ns)), 3):
        c, w1, w2 = ns[i], ns[j], ns[k]
        if is_cww(c, w1, w2):
            num_cww += 1
            cww = int(c + w1 + w2)
            nx = ''.join([ns[l] for l in range(len(ns)) if l != i and l != j and l != k])
            stack.append((score + cww, nx))

    if num_cww == 0:
        if max_score < score:
            max_score = score

print(max_score)