#pragma GCC optimize("O3") #include // clang-format off using namespace std; using ll = long long int; #define all(v) (v).begin(),(v).end() #define repeat(cnt,l) for(typename remove_const::type>::type cnt={};(cnt)<(l);++(cnt)) #define rrepeat(cnt,l) for(auto cnt=(l)-1;0<=(cnt);--(cnt)) #define iterate(cnt,b,e) for(auto cnt=(b);(cnt)!=(e);++(cnt)) #define upto(cnt,b,e,step) for(auto cnt=(b);(cnt)<=(e);(cnt)+=(step)) #define downto(cnt,b,e,step) for(auto cnt=(b);(e)<=(cnt);(cnt)-=(step)) const long long MD = 998244353; const long double PI = 3.1415926535897932384626433832795L; template inline ostream& operator <<(ostream &o, const pair p) { o << '(' << p.first << ':' << p.second << ')'; return o; } template inline T& chmax(T& to, const T& val) { return to = max(to, val); } template inline T& chmin(T& to, const T& val) { return to = min(to, val); } void bye(string s, int code = 0) { cout << s << endl; exit(code); } mt19937_64 randdev(8901016); template::value>::type* = nullptr> inline T rand(T l, T h, Random& rand = randdev) { return uniform_int_distribution(l, h)(rand); } template::value>::type* = nullptr> inline T rand(T l, T h, Random& rand = randdev) { return uniform_real_distribution(l, h)(rand); }template static ostream& operator<<(ostream& o, const std::vector& v) { o << "[ "; for(const auto& e : v) o< struct MyRangeFormat{ I b,e; MyRangeFormat(I _b, I _e):b(_b),e(_e){} }; template static ostream& operator<<(ostream& o, const MyRangeFormat& f) { o << "[ "; iterate(i,f.b,f.e) o<<*i<<' '; return o << ']'; } template struct MyMatrixFormat{ const I& p; long long n, m; MyMatrixFormat(const I& _p, long long _n, long long _m):p(_p),n(_n),m(_m){} }; template static ostream& operator<<(ostream& o, const MyMatrixFormat& f) { o<<'\n'; repeat(i,(f.n)) { repeat(j,f.m) o<(m,m+w)) #define FMTR(b,e) (MyRangeFormat(b,e)) #define FMTV(v) FMTR(v.begin(),v.end()) #define FMTM(m,h,w) (MyMatrixFormat(m,h,w)) #if defined(_WIN32) || defined(_WIN64) #define getc_x _getc_nolock #define putc_x _putc_nolock #elif defined(__GNUC__) #define getc_x getc_unlocked #define putc_x putc_unlocked #else #define getc_x getc #define putc_x putc #endif class MaiScanner { FILE* fp_; constexpr bool isvisiblechar(char c) noexcept { return (0x21<=(c)&&(c)<=0x7E); } public: inline MaiScanner(FILE* fp):fp_(fp){} template void input_integer(T& var) noexcept { var = 0; T sign = 1; int cc = getc_x(fp_); for (; cc < '0' || '9' < cc; cc = getc_x(fp_)) if (cc == '-') sign = -1; for (; '0' <= cc && cc <= '9'; cc = getc_x(fp_)) var = (var << 3) + (var << 1) + cc - '0'; var = var * sign; } inline int c() noexcept { return getc_x(fp_); } template::value, nullptr_t>::type = nullptr> inline MaiScanner& operator>>(T& var) noexcept { input_integer(var); return *this; } inline MaiScanner& operator>>(string& var) { int cc = getc_x(fp_); for (; !isvisiblechar(cc); cc = getc_x(fp_)); for (; isvisiblechar(cc); cc = getc_x(fp_)) var.push_back(cc); return *this; } template inline void in(IT begin, IT end) { for (auto it = begin; it != end; ++it) *this >> *it; } }; class MaiPrinter { FILE* fp_; public: inline MaiPrinter(FILE* fp):fp_(fp){} template void output_integer(T var) noexcept { if (var == 0) { putc_x('0', fp_); return; } if (var < 0) putc_x('-', fp_), var = -var; char stack[32]; int stack_p = 0; while (var) stack[stack_p++] = '0' + (var % 10), var /= 10; while (stack_p) putc_x(stack[--stack_p], fp_); } inline MaiPrinter& operator<<(char c) noexcept { putc_x(c, fp_); return *this; } template::value, nullptr_t>::type = nullptr> inline MaiPrinter& operator<<(T var) noexcept { output_integer(var); return *this; } inline MaiPrinter& operator<<(const char* str_p) noexcept { while (*str_p) putc_x(*(str_p++), fp_); return *this; } inline MaiPrinter& operator<<(const string& str) { const char* p = str.c_str(); const char* l = p + str.size(); while (p < l) putc_x(*p++, fp_); return *this; } template void join(IT begin, IT end, char sep = ' ') { for (bool b = 0; begin != end; ++begin, b = 1) b ? *this << sep << *begin : *this << *begin; } }; MaiScanner scanner(stdin); MaiPrinter printer(stdout); // clang-format on class Manacher { public: vector radius_; Manacher() {} Manacher(const string& str) { build(str); } void build(const string& str) { int length = str.size() * 2 - 1; radius_.resize(length); int c = 0; for (int i = 0; i < length; i++) { int l = c - (i - c); if (i + radius_[l] < c + radius_[c]) { radius_[i] = radius_[l]; } else { int j = c + radius_[c] - i; for (; i - j >= 0 && i + j < length; j++) { if (((i ^ j) & 1) == 1) continue; if (str[(i - j) / 2] != str[(i + j) / 2]) break; } radius_[i] = j; c = i; } } } inline int operator[](int idx) const { return radius_[idx]; } inline size_t size() const { return radius_.size(); } // 部分文字列str[left..right]が回文かどうか.計算量O(1) // left,rightに指定するインデックスは,基の文字列のインデックスを指定する. inline bool operator()(int left, int right) { return radius_[left + right] > right - left; } // 回文の個数を求める. long long count_num() { long long r = 0; for (auto it = radius_.begin(); it < radius_.end(); ++it, ++it) { r += (*it + 1ll) / 2ll; } for (auto it = radius_.begin() + 1; it < radius_.end(); ++it, ++it) { r += (*it) / 2ll; } return r; } // void print(const string& str) { // for (int i = 0; i < str.size(); i++) { // cout << str[i] << " "; // } // cout << endl; // for (int i = 0; i < radius_.size(); i++) { // cout << radius_[i]; // } // cout << endl; // } }; // int N; string S; Manacher manatee; // int dp[5050]; int main() { scanner >> S; N = S.size(); manatee = Manacher(S); dp[0] = MD; repeat(l, N) { const int d = dp[l]; upto(r, l, N-1, 1) { if (manatee(l, r)) { const int w = r - l + 1; chmax(dp[r+1], min(d, w)); } } } cout << dp[N]; return 0; }