結果

問題 No.2204 Palindrome Splitting (No Rearrangement ver.)
ユーザー 👑 bo9chanbo9chan
提出日時 2023-02-04 10:52:53
言語 C++23
(gcc 12.3.0 + boost 1.83.0)
結果
WA  
実行時間 -
コード長 21,106 bytes
コンパイル時間 1,963 ms
コンパイル使用メモリ 175,712 KB
実行使用メモリ 7,160 KB
最終ジャッジ日時 2024-07-03 09:28:24
合計ジャッジ時間 16,968 ms
ジャッジサーバーID
（参考情報） 		judge3 / judge4
このコードへのチャレンジ
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テストケース

テストケース表示
入力 結果 実行時間
実行使用メモリ
testcase_00 AC 2 ms
5,248 KB
testcase_01 AC 2 ms
5,376 KB
testcase_02 AC 2 ms
5,376 KB
testcase_03 WA -
testcase_04 AC 79 ms
5,376 KB
testcase_05 WA -
testcase_06 WA -
testcase_07 WA -
testcase_08 AC 450 ms
6,400 KB
testcase_09 WA -
testcase_10 AC 551 ms
7,156 KB
testcase_11 AC 437 ms
6,400 KB
testcase_12 AC 542 ms
7,140 KB
testcase_13 WA -
testcase_14 WA -
testcase_15 AC 505 ms
6,656 KB
testcase_16 WA -
testcase_17 AC 275 ms
5,504 KB
testcase_18 WA -
testcase_19 WA -
testcase_20 WA -
testcase_21 AC 553 ms
7,156 KB
testcase_22 AC 559 ms
6,944 KB
testcase_23 AC 559 ms
7,024 KB
testcase_24 AC 554 ms
7,024 KB
testcase_25 AC 562 ms
7,024 KB
testcase_26 AC 542 ms
6,948 KB
testcase_27 WA -
testcase_28 WA -
testcase_29 WA -
testcase_30 AC 1 ms
5,376 KB
testcase_31 WA -
testcase_32 AC 404 ms
6,272 KB
testcase_33 AC 548 ms
7,028 KB
testcase_34 WA -
testcase_35 AC 405 ms
6,272 KB
権限があれば一括ダウンロードができます

ソースコード

diff # 

#ifdef __LOCAL
#include <mytemplate.hpp>  // プリコンパイル済みヘッダ ~/local/include/mytemplate.hpp.gch
#else
#include <algorithm>
#include <array>
#include <bitset>
#include <cassert>
#include <climits>
#include <cmath>
#include <deque>
#include <functional>
#include <iomanip>
#include <iostream> 
#include <iterator>
#include <map>
#include <memory>
#include <numeric>
#include <queue>
#include <random>
#include <set>
#include <stack>
#include <string>
#include <utility>
#include <vector>
#endif
using namespace std;
// #include <boost/multiprecision/cpp_int.hpp>
// using bint = boost::multiprecision::cpp_int;
using int128 = __int128_t;
using ll = long long;
using vl = vector<ll>;
using vvl = vector<vl>;
using vb = vector<bool>;
using vvb = vector<vb>;
using vd = vector<double>;
using vvd = vector<vd>;
using vc = vector<char>;
using vvc = vector<vc>;
using pll = pair<ll, ll>;
#define REP1(i, n) REP3(i, 0, n, 1)
#define REP2(i, s, n) REP3(i, s, n, 1)
#define REP3(i, s, n, d) for(ll i = (ll)(s); i < (ll)(n); i += (d))
#define REP_OVERLOAD(e1, e2, e3, e4, NAME,...) NAME
#define rep(...) REP_OVERLOAD(__VA_ARGS__, REP3, REP2, REP1)(__VA_ARGS__)
#define DEP1(i, n) DEP3(i, n, -1, 1)
#define DEP2(i, n, s) DEP3(i, n, s, 1)
#define DEP3(i, n, s, d) for(ll i = (ll)(n); (ll)(s) < i; i -= (d))
#define DEP_OVERLOAD(e1, e2, e3, e4, NAME,...) NAME
#define dep(...) DEP_OVERLOAD(__VA_ARGS__, DEP3, DEP2, DEP1)(__VA_ARGS__)
#define fore(e, a) for (auto&& e: (a))
#define len(a) (ll)(a).size()
#define all(a) (a).begin(), (a).end()
#define rall(a) (a).rbegin(), (a).rend()
#define pb push_back
#define eb emplace_back
#define fi first
#define se second
#define th third
/*********    C O N S T A N T    **********/
constexpr ll INF = LONG_LONG_MAX / 2 - 10000LL;  // 4,611,686,018,427,377,903  ~= 4.6e+18, 19桁
const double PI = acos(-1);
/*********       P A I R       **********/
template<class T, class U> inline pair<T, U>& operator+=(pair<T, U>& a, const pair<T, U>& b) {a.fi += b.fi; a.se += b.se; return a;}
template<class T, class U> inline pair<T, U>& operator-=(pair<T, U>& a, const pair<T, U>& b) {a.fi -= b.fi; a.se -= b.se; return a;}
template<class T, class U> inline pair<T, U>& operator*=(pair<T, U>& a, const pair<T, U>& b) {a.fi *= b.fi; a.se *= b.se; return a;}
template<class T, class U> inline pair<T, U>& operator/=(pair<T, U>& a, const pair<T, U>& b) {a.fi /= b.fi; a.se /= b.se; return a;}
template<class T, class U> inline pair<T, U>& operator%=(pair<T, U>& a, const pair<T, U>& b) {a.fi %= b.fi; a.se %= b.se; return a;}
template<class T, class U, class V> inline pair<T, U>& operator+=(pair<T, U>& a, const V& b) {a.fi += b; a.se += b; return a;}
template<class T, class U, class V> inline pair<T, U>& operator-=(pair<T, U>& a, const V& b) {a.fi -= b; a.se -= b; return a;}
template<class T, class U, class V> inline pair<T, U>& operator*=(pair<T, U>& a, const V& b) {a.fi *= b; a.se *= b; return a;}
template<class T, class U, class V> inline pair<T, U>& operator/=(pair<T, U>& a, const V& b) {a.fi /= b; a.se /= b; return a;}
template<class T, class U, class V> inline pair<T, U>& operator%=(pair<T, U>& a, const V& b) {a.fi %= b; a.se %= b; return a;}
template<class T, class U, class V> inline pair<T, U> operator+(pair<T, U> a, const V& b) {a += b; return a;}
template<class T, class U, class V> inline pair<T, U> operator-(pair<T, U> a, const V& b) {a -= b; return a;}
template<class T, class U, class V> inline pair<T, U> operator*(pair<T, U> a, const V& b) {a *= b; return a;}
template<class T, class U, class V> inline pair<T, U> operator/(pair<T, U> a, const V& b) {a /= b; return a;}
template<class T, class U, class V> inline pair<T, U> operator%(pair<T, U> a, const V& b) {a %= b; return a;}
template<class T, class U> inline pair<T, U> operator+(pair<T, U> a) {return a;}
template<class T, class U> inline pair<T, U> operator-(pair<T, U> a) {return a * (-1);}
template<class T, class U> istream& operator >>(istream& stream, pair<T, U>& a) {stream >> a.fi >> a.se; return stream;}
template<class T, class U> ostream& operator <<(ostream &stream, const pair<T, U>& a) { stream << a.fi << " " << a.se; return stream; }
/*********       V E C T O R      **********/
template<class T> inline vector<T>& operator+=(vector<T>& a, const vector<T>& b) {assert(a.size() == b.size()); rep(i, 0, a.size()) a[i] += b[i]; return a;}
template<class T> inline vector<T>& operator-=(vector<T>& a, const vector<T>& b) {assert(a.size() == b.size()); rep(i, 0, a.size()) a[i] -= b[i]; return a;}
template<class T> inline vector<T>& operator*=(vector<T>& a, const vector<T>& b) {assert(a.size() == b.size()); rep(i, 0, a.size()) a[i] *= b[i]; return a;}
template<class T> inline vector<T>& operator/=(vector<T>& a, const vector<T>& b) {assert(a.size() == b.size()); rep(i, 0, a.size()) a[i] /= b[i]; return a;}
template<class T> inline vector<T>& operator%=(vector<T>& a, const vector<T>& b) {assert(a.size() == b.size()); rep(i, 0, a.size()) a[i] %= b[i]; return a;}
template<class T, class U> inline vector<T>& operator+=(vector<T>& a, const U& b) {fore(e, a) e += b; return a;}
template<class T, class U> inline vector<T>& operator-=(vector<T>& a, const U& b) {fore(e, a) e -= b; return a;}
template<class T, class U> inline vector<T>& operator*=(vector<T>& a, const U& b) {fore(e, a) e *= b; return a;}
template<class T, class U> inline vector<T>& operator/=(vector<T>& a, const U& b) {fore(e, a) e /= b; return a;}
template<class T, class U> inline vector<T>& operator%=(vector<T>& a, const U& b) {fore(e, a) e %= b; return a;}
template<class T, class U> inline vector<T> operator+(vector<T> a, const U& b) {a += b; return a;}
template<class T, class U> inline vector<T> operator-(vector<T> a, const U& b) {a -= b; return a;}
template<class T, class U> inline vector<T> operator*(vector<T> a, const U& b) {a *= b; return a;}
template<class T, class U> inline vector<T> operator/(vector<T> a, const U& b) {a /= b; return a;}
template<class T, class U> inline vector<T> operator%(vector<T> a, const U& b) {a %= b; return a;}
template<class T> inline vector<T> operator+(vector<T> a) {return a;}
template<class T> inline vector<T> operator-(vector<T> a) {return a * (-1);}
template<class T> istream& operator >>(istream& stream, vector<T>& a) {fore(e, a) stream >> e; return stream;}
template<class T> ostream& operator <<(ostream& stream, const vector<T>& v) {if(v.size()){stream << v[0]; rep(i, 1, v.size()) cout << " " << v[i];} return stream;}
template<class T> ostream& operator <<(ostream& stream, const vector<vector<T>>& vv) {if(vv.size()){stream << vv[0]; rep(i, 1, vv.size()) cout << '\n' << vv[i];} return stream;}
template<class T> inline T Sum(const vector<T>& v) {return reduce(all(v));}  // v.size() == 0 のとき T() を返す
template<class T> inline T Max(const vector<T>& v) {assert(v.size()); return *max_element(all(v));}
template<class T> inline T Min(const vector<T>& v) {assert(v.size()); return *min_element(all(v));}
template<class T> inline ll Argmax(const vector<T>& v) {assert(v.size()); return max_element(all(v)) - v.begin();}
template<class T> inline ll Argmin(const vector<T>& v) {assert(v.size()); return min_element(all(v)) - v.begin();}
template<class T, class U> inline bool Contains(const vector<T>& v, const U& a) {return find(all(v), a) != v.end();}
template<class T, class U> vector<T> make_vector(int n, U v) { return vector<T>(n, v); }
template <class T, class... Args> auto make_vector(int n, Args... args) {auto val = make_vector<T>(args...); return make_vector<decltype(val)>(n, move(val));}
/*********        S E T        **********/
template<class T> istream& operator >>(istream& stream, set<T>& st) {T e; stream >> e; st.insert(e); return stream;}
template<class T> ostream& operator <<(ostream& stream, const set<T>& st) {if(st.size()){auto it=st.begin(); stream << *it++; for(; it!=st.end(); it++) cout << " " << *it;} return stream;}
template<class T> inline T Max(const set<T>& st) {assert(st.size()); return *prev(st.end());}
template<class T> inline T Min(const set<T>& st) {assert(st.size()); return *st.begin();}
template<class T> inline bool Contains(const set<T>& st, T x) {return st.find(x) != st.end();}
/*********   M U L T I S E T   **********/
template<class T> istream& operator >>(istream& stream, multiset<T>& st) {T e; stream >> e; st.insert(e); return stream;}
template<class T> ostream& operator <<(ostream& stream, const multiset<T>& st) {if(st.size()){auto it=st.begin(); stream << *it++; for(; it!=st.end(); it++) cout << " " << *it;} return stream;}
template<class T> inline T Max(const multiset<T>& st) {assert(st.size()); return *prev(st.end());}
template<class T> inline T Min(const multiset<T>& st) {assert(st.size()); return *st.begin();}
template<class T> inline bool Contains(const multiset<T>& st, T x) {return st.find(x) != st.end();}
template<class T> inline bool EraseOne(multiset<T>& st, T x) {auto it=st.find(x); if (it!=st.end()) {st.erase(it); return true;} else return false;}  // 要素xを1つ削除. 消せたらtrueを返す.
/*********     S T R I N G     **********/
template<class T> inline bool Contains(const string& s, const T& c) {return s.find(c) != string::npos;}  // cはchar, string共に可
inline string ToUpper(const string& s) {string t; t.resize(s.size()); std::transform(all(s), t.begin(), ::toupper); return t; }
inline string ToLower(const string& s) {string t; t.resize(s.size()); std::transform(all(s), t.begin(), ::tolower); return t; }
/*********       T R I O       **********/
template<class T1, class T2, class T3> struct trio {
    T1 first; T2 second; T3 third;
    // コンストラクタ・代入演算子
    trio() {first=T1(); second=T2(); third=T3();}
    trio(const T1& x) : first(x), second(x), third(x) {}
    trio(const T1& x, const T2& y, const T3& z) : first(x), second(y), third(z) {}
    trio(const trio& t) {first=t.first; second=t.second; third=t.third;}  // コピーコンストラクタ
    trio& operator =(const trio& t) {first=t.first; second=t.second; third=t.third; return *this;}
    // 比較演算子
    bool operator <(const trio& t) const {return tie(first, second, third) < tie(t.first, t.second, t.third);}
    bool operator ==(const trio& t) const {return tie(first, second, third) == tie(t.first, t.second, t.third);}
    bool operator !=(const trio& other) const { return !(*this == other); }
    bool operator >(const trio& other) const { return other < *this; }
    bool operator <=(const trio& other) const { return !(*this > other); }
    bool operator >=(const trio& other) const { return !(*this < other); }
    // 単項演算子（+ -）
    trio operator +() const { return *this; }
    trio operator -() const { return (-1) * (*this); }
    // 複合代入演算子
    trio& operator +=(const trio& t) {first += t.first; second += t.second; third += t.third; return *this;}
    trio& operator -=(const trio& t) {first -= t.first; second -= t.second; third -= t.third; return *this;}
    trio& operator *=(const trio& t) {first *= t.first; second *= t.second; third *= t.third; return *this;}
    trio& operator /=(const trio& t) {first /= t.first; second /= t.second; third /= t.third; return *this;}
    trio& operator %=(const trio& t) {first %= t.first; second %= t.second; third %= t.third; return *this;}
    // 算術演算子
    friend trio operator +(const trio& lhs, const trio& rhs) {return trio(lhs) += rhs;}
    friend trio operator -(const trio& lhs, const trio& rhs) {return trio(lhs) -= rhs;}
    friend trio operator *(const trio& lhs, const trio& rhs) {return trio(lhs) *= rhs;}
    friend trio operator /(const trio& lhs, const trio& rhs) {return trio(lhs) /= rhs;}
    friend trio operator %(const trio& lhs, const trio& rhs) {return trio(lhs) %= rhs;}
    // 入出力
    friend istream& operator >>(istream &stream, trio& t) {return stream >> t.first >> t.second >> t.third;}
    friend ostream& operator <<(ostream &stream, const trio& t) {return stream << t.first << " " << t.second << " " << t.third;}
};
using tll = trio<ll, ll, ll>;
/*********       P R I N T       **********/
template<class T> inline void print(const T& e) {cout << e << '\n';}
template<class H, class... T> inline void print(const H& h, const T&... t) {cout << h << ' '; print(t...);}
template<class... T> inline void End(const T&... t) {print(t...); exit(0);}
/*********       D E B U G       **********/
#ifdef __LOCAL
#define debug(...) if(DEBUG) do{cout << '[' << #__VA_ARGS__ << "] ";debug_(__VA_ARGS__);}while(0)
#else
#define debug(...)
#endif
void dbg_(const long long& e) {if (e == INF) cout << "INF"; else if (e == -INF) cout << "-INF"; else cout << e;}
template<class T> void dbg_(const T& e) {cout << e;}
template<class T, class U> void dbg_(const pair<T, U>& p) {cout << '('; dbg_(p.first); cout << ' '; dbg_(p.second); cout << ')';}
template<class T1, class T2, class T3> void dbg_(const trio<T1, T2, T3>& t) {cout << '('; dbg_(t.first); cout << ' '; dbg_(t.second); cout << ' '; dbg_(t.third); cout << ')';}
template<class T> void debug_(const T& e) {dbg_(e); cout << '\n';}
template<class T> void debug_(const vector<T>& v) {if (v.size()){auto it=v.begin(); dbg_(*it++); for(; it!=v.end(); ++it){cout << ' '; dbg_(*it);}} cout << '\n';}
template<class T> void debug_(const vector<vector<T>>& vv) {cout << '\n'; ll cnt=0; for(auto&& v : vv){cout << cnt++ << ": "; debug_(v);}}
template<class T, class U> void debug_(const map<T, U>& mp) {if (mp.size()) {auto it = mp.begin(); dbg_(*it++); for(; it != mp.end(); ++it) {cout << ' '; dbg_(*it);}} cout << '\n';}
template<class T, class U> void debug_(const vector<map<T, U>>& vm){cout << '\n'; ll cnt=0; for(auto&& mp : vm){cout << cnt++ << ": "; debug_(mp);}}
template<class T> void debug_(const set<T>& st) {if(st.size()){auto it=st.begin(); dbg_(*it++); for(; it!=st.end(); ++it) {cout << ' '; dbg_(*it);}}cout << '\n';}
template<class T> void debug_(const multiset<T>& st) {if(st.size()) {auto it=st.begin(); dbg_(*it++); for(; it != st.end(); ++it) {cout << ' '; dbg_(*it);}} cout << '\n';}
template<class T> void debug_(const vector<set<T>>& vs) {cout << '\n'; ll cnt=0; for(auto&& st : vs){cout << cnt++ << ": "; debug_(st);}}
template<class T> void debug_(const vector<multiset<T>>& vs) {cout << '\n'; ll cnt=0;for(auto&& st : vs){cout << cnt++ << ": "; debug_(st);}}
template<class H, class... T> void debug_(const H& h, const T&... t) {dbg_(h); cout << ", "; debug_(t...);}
/*********       O T H E R S       **********/
template<class T, class U> inline bool chmin(T& a, U b) {if (a > b) {a = b; return true;} return false;}  // bは値渡し!
template<class T, class U> inline bool chmax(T& a, U b) {if (a < b) {a = b; return true;} return false;}
template<class T, class U> inline auto Mod(const T& a, const U& m) {return (a % m + m) % m;}  // 負もOK
template<class T, class U> inline auto Ceil(const T& x, const U& y) {return x < 0 ? x/y : (x + y - 1) / y;}  // 負もOK
template<class T, class U> inline auto Floor(const T& x, const U& y) {return -(Ceil(-x, y)); }  // 負もOK
inline ll isqrt(ll n) {assert(n >= 0); ll x = round(sqrt(n)); while(x * x > n) --x; return x;}
template<class T> inline T Pow(T x, ll n) {assert(n >= 0); T ret = 1; while(1) {if (n % 2) ret *= x; n /= 2; if(!n) return ret; x = x * x;}}  // べき乗 mintもOK
template<class T> inline T Aseries(T a, T d, ll n) {assert(n >= 0); return a * n + n * (n - 1) / 2 * d;}  // 等差級数 mintもOK
template<class T> inline T Gseries(T a, T r, ll n) {assert(n >= 0); if (r == 1) return a * n; else return a * (1 - Pow(r, n)) / (1 - r);}  // 等比級数 mintもOK
template<class T> using min_priority_queue = priority_queue<T, vector<T>, greater<T>>;
inline bool Bit(ll b, int i) {assert(0 <= i && i < 64); return (b >> i) & 1;}
inline ll Popcount(ll b) {return __builtin_popcountll(b);}
inline ll Mask(ll n) {assert(0 <= n && n < 63); return (1LL << n) - 1LL;}  // [0, n)のbitが立った64bit整数を返す。
inline ll Mask(ll n, ll m) {assert(n >= m); return Mask(n) ^ Mask(m);}  // [m, n)のbitが立った64bit整数を返す。
/*********       M  O  D       **********/
// #include <atcoder/modint>  // https://atcoder.github.io/ac-library/production/document_ja/
// using namespace atcoder;
// using mint = modint998244353;     // modint1000000007;
// istream& operator >>(istream& stream, mint& e) {ll n; stream >> n; e = n; return stream; }
// ostream& operator <<(ostream& stream, const mint& e) { stream << e.val(); return stream; }
// using vm = vector<mint>;
// using vvm = vector<vm>;
/***************************************/
constexpr bool DEBUG = false;


// AOJでverify済 https://onlinejudge.u-aizu.ac.jp/problems/ALDS1_14_B
// RollingHashを計算
// 参考：https://qiita.com/keymoon/items/11fac5627672a6d6a9f6
struct RollingHash {
    using int128_t = __int128_t;  // GCC
    // using int128_t = boost::multiprecision::int128_t;  // Boost

    const ll P = 61;
    const int128_t BASE = 368789449308LL;  // 基数, 2^61-1の原始根
    const int128_t MOD = (1LL << P) - 1;  // modulo, 法
    ll N;  // 文字列／配列の長さ
    vector<int128_t> B;  // B[i] : BASE ^ i;
    vector<int128_t> H;  // H[a] : S[0..a]（先頭a文字）のハッシュ値

    // (a + b) % MODを計算 (a, bは 0 以上 MOD 未満)
    ll Add(ll a, ll b) const {
        assert(0 <= a && a < MOD && 0 <= b && b < MOD);
        ll ret = a + b;
        return (ret >= MOD) ? ret - MOD : ret;
    }

    // (a * b) % MOD を計算
    int128_t Mul(int128_t a, int128_t b) const {
        int128_t t = a * b;
        // u, v < 2^Pとして、t = u * 2^P + v ≡ u + v mod. 2^P - 1 (∵ 2^P ≡ 1)
        int128_t ret = (t >> P) + (t & MOD);
        return (ret >= MOD) ? ret - MOD : ret;
    }

    RollingHash() {}
    RollingHash(const string& S, char c=0) {
        N = len(S);
        B.resize(N + 1); B[0] = 1;
        H.resize(N + 1); H[0] = 0;
        rep(i, 1, N + 1) B[i] = Mul(B[i - 1], BASE);
        rep(i, 1, N + 1) assert(S[i - 1] > c);
        rep(i, 1, N + 1) H[i] = Add(Mul(H[i - 1], BASE), S[i - 1] - c);
    }

    RollingHash(const vl& A) {
        N = len(A);
        B.resize(N + 1); B[0] = 1;
        H.resize(N + 1); H[0] = 0;
        rep(i, 1, N + 1) B[i] = Mul(B[i - 1], BASE);
        rep(i, 1, N + 1) assert(A[i - 1] > 0);
        rep(i, 1, N + 1) H[i] = Add(Mul(H[i - 1], BASE), A[i - 1]);
    }
  
    // 代入演算子
    RollingHash& operator =(const RollingHash& other) {
        N = other.N; B = other.B; H = other.H;
        return *this;
    }

    // S[a:b]のハッシュ値, ret = (H[b] - H[a] * B[b - a]) % MOD
    ll operator() (ll a, ll b) const {
        assert(0 <= a && a <= b && b <= N);
        auto tmp = Mul(H[a], B[b - a]);
        ll ret = Add(H[b], Mul(MOD - 1, tmp));  // MOD - 1 ≡ -1
        return ret;
    }

    // S[a1:b1] + S[a2:b2]のハッシュ値.
    ll operator() (ll a1, ll b1, ll a2, ll b2) const {
        assert(0 <= a1 && a1 <= b1 && b1 <= a2 && a2 <= b2 && b2 <= N);
        ll ret = Add(Mul((*this)(a1, b1), B[b2 - a2]), (*this)(a2, b2));
        return ret;
    }

    // Sのハッシュ値
    ll operator() () const {
        return (*this)(0, N);
    }

    // 左シフト（巡回）, S[i:N] + S[0:i]
    ll lshift(ll i) const {
        ll j = Mod(i, N);
        ll ret = Add(Mul((*this)(j, N), B[j]), (*this)(0, j));
        return ret;
    }

    // 右シフト（巡回）, S[N-i:N] + S[0:N-i]
    ll rshift(ll i) const {
        return lshift(N - i);
    }
};
// string S = "abcde";
// RollingHash rh(S);
// ll h1 = rh(1, 3);        // S[1:3] (ab)のハッシュ値
// ll h2 = rh(0, 2, 3, 4);  // S[0:2] + S[3:4]（abd）
// ll h3 = rh();            // S（abcde）
// ll h4 = rh.lshift(2);    // S[2:] + s[:2]（cdeab）
// ll h5 = rh.rshift(2);    // S[3:] + s[:3]（deabc）

int main() {
    cin.tie(nullptr); cout << fixed << setprecision(10);

    string S;
    cin >> S;
    ll N = len(S);
    auto rS(S);
    reverse(all(rS));
    RollingHash rh1(S), rh2(rS);

    auto P = make_vector<bool>(N + 1, N + 1, false);

    rep(l, N + 1) {
        rep(r, l + 1, N + 1) {
            ll l2 = N - r;
            ll r2 = N - l;
            if (rh1(l, r) == rh2(l2, r2)) P[l][r] = true;
        }
    }
    debug(P);

    auto dp = make_vector<ll>(N + 1, -INF);
    dp[0] = 0;
    rep(i, N) {
        if (dp[i] == -INF) continue;
        rep(j, i + 1, N + 1) {
            if (P[i][j]) chmax(dp[j], j - i);
        }
    }
    print(dp[N]);

}

    // auto dp = make_vector<ll>(N + 1, N + 1, 0);
    // auto seen = make_vector<bool>(N + 1, N + 1, false);

    // auto dfs = [&](auto&& f, ll l, ll r) -> ll {
    //     if (seen[l][r]) return dp[l][r];
    //     seen[l][r] = true;
    //     if (P[l][r]) {
    //         return dp[l][r] = r - l;
    //     }
    //     ll ret = 0;
    //     rep(m, l + 1, r) {
    //         ll n1 = f(f, l, m);
    //         ll n2 = f(f, m, r);
    //         chmax(ret, min(n1, n2));
    //     }
    //     return dp[l][r] = ret;
    // };
    // ll ans = dfs(dfs, 0, N);
    // debug(dp);
    // print(ans);
0