#include <atcoder/all>
using namespace atcoder;
#include <bits/stdc++.h>
using namespace std;
// #include <boost/multiprecision/cpp_int.hpp>
#pragma GCC target("avx2")
#pragma GCC optimize("O3")
#pragma GCC optimize("unroll-loops")
#define rep(i, n) for (int i = 0; i < (int)(n); i++)
#define rep2(i,a,b) for (int i = (int)(a); i < (int)(b); i++)
#define all(v) v.begin(),v.end()
#define inc(x,l,r) ((l)<=(x)&&(x)<(r)) 
#define Unique(x) sort(all(x)), x.erase(unique(all(x)), x.end())
#define pcnt __builtin_popcountll
typedef long long ll;
#define int ll
using ld = long double;
using vi = vector<int>;
using vs = vector<string>;
using P = pair<int,int>;
using vp = vector<P>;
// using Bint = boost::multiprecision::cpp_int;
template<typename T1,typename T2> bool chmax(T1 &a, const T2 b) {if (a < b) {a = b; return true;} else return false; }
template<typename T1,typename T2> bool chmin(T1 &a, const T2 b) {if (a > b) {a = b; return true;} else return false; }
template<typename T> using priority_queue_greater = priority_queue<T, vector<T>, greater<T>>;
template<typename T> ostream &operator<<(ostream &os,const vector<T> &v){rep(i,v.size())os<<v[i]<<(i+1!=v.size()?" ":"");return os;}
template<typename T> istream &operator>>(istream& is,vector<T> &v){for(T &in:v)is>>in;return is;}
template<typename T1,typename T2> ostream &operator<< (ostream &os, const pair<T1,T2> &p){os << p.first <<" "<<p.second;return os;}
ostream &operator<< (ostream &os, const modint1000000007 &m){os << m.val();return os;}
istream &operator>> (istream &is, modint1000000007 &m){ll in;is>>in;m=in;return is;}
ostream &operator<< (ostream &os, const modint998244353 &m){os << m.val();return os;}
istream &operator>> (istream &is, modint998244353 &m){ll in;is>>in;m=in;return is;}
template<class... T> void input(T&... a){(cin>> ... >> a);}
template<class T> void print(T& a){cout <<a<< '\n';}
template<class T,class... Ts> void print(const T&a, const Ts&... b){cout<< a;(cout<<...<<(cout<<' ',b));cout<<'\n';}
#define VI(v,n) vi v(n); input(v)
#define INT(...) int __VA_ARGS__; input(__VA_ARGS__)
#define STR(...) string __VA_ARGS__; input(__VA_ARGS__)
#define CHAR(...) char __VA_ARGS__; input(__VA_ARGS__)
int sign(int x){return x>0?1:x<0?-1:0;}
int ceil(int x,int y){assert(y!=0);if(sign(x)==sign(y))return (x+y-1)/y;return -((-x/y));}
int floor(int x,int y){assert(y!=0);if(sign(x)==sign(y))return x/y;if(y<0)x*=-1,y*=-1;return x/y-(x%y<0);}
int abs(int x,int y){return abs(x-y);}
bool ins(string s,string t){return s.find(t)!=string::npos;}
P operator+ (const P &p, const P &q){ return P{p.first+q.first,p.second+q.second};}
P operator- (const P &p, const P &q){ return P{p.first-q.first,p.second-q.second};}
void yesno(bool ok,string y="Yes",string n="No"){ cout<<(ok?y:n)<<endl;}
void YESNO(bool ok,string y="YES",string n="NO"){ cout<<(ok?y:n)<<endl;}
int di[]={-1,0,1,0,-1,-1,1,1};
int dj[]={0,1,0,-1,-1,1,-1,1};
const ll INF = 8e18;
//using mint = modint1000000007;
//using mint = modint998244353;
//mint stom(const string &s,int b=10){mint res = 0;for(auto c:s)res *= b,res += c-'0';return res;}
//https://betrue12.hateblo.jp/entry/2019/09/16/013915
template<bool use_reverse = false>
struct RollingHash{
    vector<ll> hash;
    vector<ll> hash_rev;
    vector<ll> base_pow;
    ll base, mod;
    const ll DEFAULT_BASE = 1009, DEFAULT_MOD = 1e9+7;
 
    RollingHash(string S="", ll base_=-1, ll mod_=-1){
        base = base_ > 0 ? base_ : DEFAULT_BASE;
        mod = mod_ > 0 ? mod_ : DEFAULT_MOD;
        if(S.size() > 0) initialize(S);
    }
 
    void initialize(string& S){
        int N = S.size();
        vector<int> s(N);
        for(int i=0; i<N; i++) s[i] = S[i];
        initialize(s);
    }
 
    void initialize(vector<int>& S){
        hash.resize(S.size()+1);
        hash[0] = 0;
        vector<int> S_rev;
        if(use_reverse){
            S_rev = S;
            reverse(all(S_rev));
            hash_rev.resize(S.size()+1);
            hash_rev[0] = 0;
        }
        base_pow.resize(S.size()+1);
        base_pow[0] = 1;
        for(int i=1; i<=S.size(); i++){
            hash[i] = (hash[i-1] * base + S[i-1]) % mod;
            if(use_reverse)hash_rev[i] = (hash_rev[i-1] * base + S_rev[i-1]) % mod;
            base_pow[i] = base_pow[i-1] * base % mod;
        }
    }
 
    // 0-indexed, [l, r)
    ll between(int l, int r,bool rev = false){
        if(rev){
            assert(use_reverse);
            return (mod + hash_rev[hash.size()-l-1] - hash_rev[hash.size()-r-1] * base_pow[r-l] % mod) % mod;
        } 
        else return (mod + hash[r] - hash[l] * base_pow[r-l] % mod) % mod;
    }
    bool ispalindrome(int l,int r){
        return between(l,r) == between(l,r,true);
    }
};
signed main() {
    cin.tie(0);
    ios_base::sync_with_stdio(false);
    cout << fixed << setprecision(20);

    STR(s);
    int n = s.size();
    RollingHash<true> rh(s);
    vector<vp> G(n+1);
    rep(l,n)for(int r=l+1;r<=n;r++)if(rh.ispalindrome(l,r))G[l].push_back({r,r-l});
    int ok = 1;
    int ng = n+1;
    auto f = [&](int m){
        //長さm以上のみ使える
        vi dp(n+1);
        dp[0] = 1;
        rep(i,n)if(dp[i]){
            for(auto [j,len]:G[i]){
                if(len<m)continue;
                dp[j]=true;
            }
        }
        return dp[n];
    };
    while(abs(ng-ok)>1){
        int mid = ng+(ok-ng)/2;
        if(f(mid))ok=mid;
        else ng = mid;
    }
    print(ok);
    return 0;
}