import sys
input = sys.stdin.readline

S=input().strip()

DP=[[0]*(len(S)+3) for i in range(len(S)+3)]

for i in range(len(S)):
    for j in range(len(S)-1,i,-1):
        DP[i][j]=max(DP[i][j],DP[i-1][j+1])

        if S[i]==S[j]:
            DP[i][j]+=1

ANS=0
for i in range(len(S)):
    for j in range(i+1,len(S)):
        if j%2==i%2:
            ANS=max(ANS,DP[i][j]*2+1)
        else:
            ANS=max(ANS,DP[i][j]*2)

print(ANS)