A = tuple([int(s) for s in input()])
from functools import lru_cache
@lru_cache(maxsize=1000000)
def f(X):
    N = len(X)
    if N < 3:
        return 0
    ret = 0
    Y1 = list(X)
    Y1.pop(0)
    for i in range(1,N-1):
        Y2 = Y1[:]
        Y2.pop(i-1)
        for j in range(i+1,N):
            Y3 = Y2[:]
            Y3.pop(j-2)
            tmp = 0
            if X[i] == X[j]:
                tmp += X[0] * 100 + X[i] * 10 + X[i]
            tmp += f(tuple(Y3))
            ret = max(ret,tmp)
    return ret
print(f(A))