N = str(int(input()))[::-1]
high_score = [0]

def hoge(s, score):
    for i, c1 in enumerate(s):
        for j, c2 in enumerate(s[i+1:], start=i+1):
            if c1 != c2:
                continue
            for k, c3 in enumerate(s[j+1:], start=j+1):
                if c1 == c3:
                    continue
                hoge(s[:i]+s[i+1:j]+s[j+1:k]+s[k+1:], score+int(c3+c2+c1))
    if score > high_score[0]:
        high_score[0] = score

hoge(N, 0)
print(high_score[0])