t = input()
n = len(t)
aa = [int(c) for c in t]

def dfs(i, s):
    if i == n - 2: return 0
    if s >> i & 1: return dfs(i + 1, s)
    res = dfs(i + 1, s)
    for j in range(i + 1, n - 1):
        if s >> j & 1: continue
        if aa[i]==aa[j]:continue
        for k in range(j + 1, n):
            if s >> k & 1: continue
            if aa[j] == aa[k]:
                ns = s | 1 << j | 1 << k
                cur = 100 * aa[i] + 11 * aa[j] + dfs(i + 1, ns)
                res = max(res, cur)
    return res

print(dfs(0, 0))