import sys
input=lambda: sys.stdin.readline().rstrip()
S=input()
n=len(S)
ans=1
for i in range(n):
  for j in range(i+1,n+1):
    if j-i<=ans:
      continue
    else:
      SS=S[i:j]
      if SS==SS[::-1]:
        ans=j-i
print(min(ans,n-1))