// includes
#include <bits/stdc++.h>
using namespace std;

// macros
#define pb emplace_back
#define mk make_pair
#define FOR(i, a, b) for(int i=(a);i<(b);++i)
#define rep(i, n) FOR(i, 0, n)
#define rrep(i, n) for(int i=((int)(n)-1);i>=0;i--)
#define irep(itr, st) for(auto itr = (st).begin(); itr != (st).end(); ++itr)
#define irrep(itr, st) for(auto itr = (st).rbegin(); itr != (st).rend(); ++itr)
#define all(x) (x).begin(),(x).end()
#define sz(x) ((int)(x).size())
#define UNIQUE(v) v.erase(unique(v.begin(), v.end()), v.end())
#define bit(n) (1LL<<(n))
// functions
template <class T>bool chmax(T &a, const T &b){if(a < b){a = b; return 1;} return 0;}
template <class T>bool chmin(T &a, const T &b){if(a > b){a = b; return 1;} return 0;}
template <typename T> istream &operator>>(istream &is, vector<T> &vec){for(auto &v: vec)is >> v; return is;}
template <typename T> ostream &operator<<(ostream &os, const vector<T>& vec){for(int i = 0; i < vec.size(); i++){ os << vec[i]; if(i + 1 != vec.size())os << " ";} return os;}
template <typename T> ostream &operator<<(ostream &os, const set<T>& st){for(auto itr = st.begin(); itr != st.end(); ++itr){ os << *itr; auto titr = itr; if(++titr != st.end())os << " ";} return os;}
template <typename T> ostream &operator<<(ostream &os, const unordered_set<T>& st){for(auto itr = st.begin(); itr != st.end(); ++itr){ os << *itr; auto titr = itr; if(++titr != st.end())os << " ";} return os;}
template <typename T> ostream &operator<<(ostream &os, const multiset<T>& st){for(auto itr = st.begin(); itr != st.end(); ++itr){ os << *itr; auto titr = itr; if(++titr != st.end())os << " ";} return os;}
template <typename T> ostream &operator<<(ostream &os, const unordered_multiset<T>& st){for(auto itr = st.begin(); itr != st.end(); ++itr){ os << *itr; auto titr = itr; if(++titr != st.end())os << " ";} return os;}
template <typename T1, typename T2> ostream &operator<<(ostream &os, const pair<T1, T2> &p){os << p.first << " " << p.second; return os;}
template <typename T1, typename T2> ostream &operator<<(ostream &os, const map<T1, T2> &mp){for(auto itr = mp.begin(); itr != mp.end(); ++itr){ os << itr->first << ":" << itr->second; auto titr = itr; if(++titr != mp.end())os << " "; } return os;}
template <typename T1, typename T2> ostream &operator<<(ostream &os, const unordered_map<T1, T2> &mp){for(auto itr = mp.begin(); itr != mp.end(); ++itr){ os << itr->first << ":" << itr->second; auto titr = itr; if(++titr != mp.end())os << " "; } return os;}
//  types
using ll = long long int;
using P = pair<int, int>;
// constants
const int inf = 1e9;
const ll linf = 1LL << 50;
const double EPS = 1e-10;
const int mod = 1000000007;
const int dx[4] = {-1, 0, 1, 0};
const int dy[4] = {0, -1, 0, 1};
// io
struct fast_io{
  fast_io(){ios_base::sync_with_stdio(false); cin.tie(0); cout << fixed << setprecision(20);}
} fast_io_;

struct Node{
  map<char, int> next;
  int len = 0;
  int suffixlink = -1;
  int cnt = 0;
  Node(int len, int suffixlink): len(len), suffixlink(suffixlink){}
};

struct PalindromicTree{
  string s;
  vector<Node> tree;
  int curr = 0;
  vector<int> max_suffix_idx;
  PalindromicTree(const string &s): s(s){
    tree.reserve(s.size() + 2);
    curr = 2;
    tree.emplace_back(-1, 0);
    tree.emplace_back(0, 0);
    max_suffix_idx.resize(s.size() + 2, 1);
    for(size_t i = 0; i < s.size(); i++){
      addl(i);
    }
  }
  // true if added, false if exists
  bool addl(int i){
    int A = max_suffix_idx[i+1];
    while(true){
      if(i - 1 - tree[A].len >= 0 && s[i - 1 - tree[A].len] == s[i])break;
      A = tree[A].suffixlink;
    }

    if(tree[A].next[s[i]] != 0){
      max_suffix_idx[i + 2] = tree[A].next[s[i]];
      return false;
    }

    max_suffix_idx[i + 2] = curr;
    tree[A].next[s[i]] = curr;
    curr++;
    tree.emplace_back(tree[A].len + 2, -1);

    if(tree.back().len == 1){
      tree.back().suffixlink = 1;
      tree.back().cnt = 1;
      return true;
    }

    int B = A;
    while(true){
      B = tree[B].suffixlink;
      if(i - 1 - tree[B].len >= 0 && s[i - 1 - tree[B].len] == s[i])break;
    }
    tree.back().suffixlink = tree[B].next[s[i]];
    tree.back().cnt = 1 + tree[tree.back().suffixlink].cnt;
    return true;
  }
};


int main(int argc, char const* argv[])
{
  string s; cin >> s;
  PalindromicTree pt(s);
  int res = 1;
  rep(i, sz(s)){
    if(pt.tree[pt.max_suffix_idx[i+2]].len != sz(s)){
      res = max(res, pt.tree[pt.max_suffix_idx[i+2]].len);
    }
  }
  cout << res << endl;
  return 0;
}