N = input()
l = len(N)

lst = []
for i in range(l):
    for j in range(i + 1, l):
        for k in range(j + 1, l):
            if N[i] != "0" and N[i] != N[j] and N[j] == N[k]:
                bit = (1 << i) | (1 << j) | (1 << k)
                lst.append((bit, int(N[i] + N[j] + N[k])))

dp = [0] * (1 << l)
for bit in range(1 << l):
    for b, c in lst:
        if bit & b == 0:
            dp[bit | b] = max(dp[bit | b], dp[bit] + c)
print(max(dp))