from string import ascii_lowercase

X=ascii_lowercase+"0123456789"
D={x:[] for x in X}

S=input()
N=len(S)

for i in range(N):
    D[S[i]].append(i)

#長さが奇数
K=0
for i in range(N):
    e=1
    A=1
    while 0<=i-e and i+e<N:
        if S[i-e]==S[i+e]:A+=2
        e+=1
    if K<A:K=A

#長さが偶数
for x in D:
    E=D[x]
    L=len(E)

    for i in range(L):
        p=E[i]
        for j in range(i+1,L):
            e=1
            A=2
            q=E[j]
            while 0<=p-e and q+e<N:
                if S[p-e]==S[q+e]:A+=2
                e+=1
            if K<A:K=A

print(K)