template `max=`*(x,y) = x = max(x,y)
let S = stdin.readLine()
if S.len <= 2 : quit "-1",0
var ans = 1
for i in 1..<S.len-1:
  var iAns = 1
  for j in 1..S.len:
    if i-j < 0 or i+j >= S.len: break
    if S[i-j] == S[i+j] : iAns += 2
  ans .max= iAns
echo ans