s = input(); n = len(s)
rl = [{i-1} for i in range(n)]
for i in range(n-1):
    if s[i]==s[i+1]: rl[i+1].add(i-1)
for d in range(3,n+1):
    for l in range(-1,n-d):
        if s[l+1]==s[l+d] and l+1 in rl[l+d-1]: rl[l+d].add(l)
dp = [0]*n+[n]
for r in range(n):
    for l in rl[r]: dp[r] = max(dp[r],min(dp[l],r-l))
print(dp[n-1])