s = input()
n = len(s)

ok = [[False for _ in range(n + 1)] for _ in range(n + 1)]
for i in range(n):
  ok[i + 1][i + 1] = True
  if i < n - 1 and s[i] == s[i + 1]:
    ok[i + 1][i + 2] = True

for d in range(3, n + 1):
  for l in range(n + 1 - d):
    r = l + d - 1
    if ok[l + 2][r] and s[l] == s[r]:
      ok[l + 1][r + 1] = True

dp = [0 for _ in range(n + 1)]
dp[0] = 1 << 60
dp[1] = 1
for r in range(2, n + 1):
  for l in range(r):
    if ok[l + 1][r]:
      dp[r] = max(dp[r], min(dp[l], r - l))

print(dp[-1])