from functools import lru_cache

@lru_cache(maxsize=10**6)
def f(L):
    X=0
    N=len(L)
    for i in range(N):
        if L[i]=="0":
            continue

        for j in range(i+1,N):
            for k in range(j+1,N):
                if L[j]==L[k]:
                    B=L[:i]+L[i+1:j]+L[j+1:k]+L[k+1:]
                    X=max(100*int(L[i])+11*int(L[j])+f(B),X)
    return X

S=input()
print(f(S))