#include using namespace std; #define ALL(x) x.begin(),x.end() #define rep(i,n) for(int i=0;i<(n);i++) #define debug(v) cout<<#v<<":";for(auto x:v){cout<bool chmax(T &a,const T &b){if(abool chmin(T &a,const T &b){if(b ostream &operator<<(ostream &os,const pair&p){ os< ostream &operator<<(ostream &os,const vector&v){ for(int i=0;i<(int)v.size();i++) os< istream &operator>>(istream &is,pair&p){ is>>p.first>>p.second; return is; } template istream &operator>>(istream &is,vector&v){ for(T &x:v)is>>x; return is; } // hash type using ull=unsigned long long; struct RollingHash{ using ull=unsigned long long; using uint128=__uint128_t; static const ull MOD=(1ull<<61ull)-1; vectorhashed,power; const ull base; static inline ull add(ull a,ull b){if((a+=b)>=MOD)a-=MOD;return a;} static inline ull mul(ull a,ull b){uint128 c=(uint128)a*b;return add(c>>61,c&MOD);} static inline ull generate_base(){ mt19937_64 mt(chrono::steady_clock::now().time_since_epoch().count()); uniform_int_distributionrand(1,RollingHash::MOD-1); return rand(mt); } RollingHash()=default; RollingHash(const string &s,ull base):base(base){ int sz=(int)s.size(); hashed.assign(sz+1,0); power.assign(sz+1,0); power[0]=1; for(int i=0;i RollingHash(const vector&s,ull base):base(base){ int sz=(int)s.size(); hashed.assign(sz+1,0); power.assign(sz+1,0); power[0]=1; for(int i=0;i1){ int mid=(lw+hi)/2; if(get(l1,l1+mid)==b.get(l2,l2+mid))lw=mid; else hi=mid; } return lw; } }; template struct ModInt{ long long x; ModInt():x(0){} ModInt(long long y):x(y>=0?y%Mod:(Mod-(-y)%Mod)%Mod){} ModInt &operator+=(const ModInt &p){ if((x+=p.x)>=Mod) x-=Mod; return *this; } ModInt &operator-=(const ModInt &p){ if((x+=Mod-p.x)>=Mod)x-=Mod; return *this; } ModInt &operator*=(const ModInt &p){ x=(int)(1ll*x*p.x%Mod); return *this; } ModInt &operator/=(const ModInt &p){ (*this)*=p.inverse(); return *this; } ModInt operator-()const{return ModInt(x);} ModInt operator+(const ModInt &p)const{return ModInt(*this)+=p;} ModInt operator-(const ModInt &p)const{return ModInt(*this)-=p;} ModInt operator*(const ModInt &p)const{return ModInt(*this)*=p;} ModInt operator/(const ModInt &p)const{return ModInt(*this)/=p;} ModInt operator==(const ModInt &p)const{return x==p.x;} ModInt operator!=(const ModInt &p)const{return x!=p.x;} ModInt inverse()const{ int a=x,b=Mod,u=1,v=0,t; while(b>0){ t=a/b; swap(a-=t*b,b);swap(u-=t*v,v); } return ModInt(u); } ModInt pow(long long n)const{ ModInt ret(1),mul(x); while(n>0){ if(n&1) ret*=mul; mul*=mul;n>>=1; } return ret; } friend ostream &operator<<(ostream &os,const ModInt &p){return os<>(istream &is,ModInt &a){long long t;is>>t;a=ModInt(t);return (is);} static int get_mod(){return Mod;} }; using mint=ModInt; template struct comcalc{ vector fact,finv,inv; comcalc():fact(MAX),finv(MAX),inv(MAX){ fact[0]=mint(1),fact[1]=mint(1),finv[0]=mint(1),finv[1]=mint(1),inv[1]=mint(1); for(int i=2;in-r) r=n-r; if(r==0) return 1; mint a=1,b=mint(fact_mod(r)).inverse(); for(int i=0;i; signed main(){ string s;cin>>s; int n=(int)s.size(); auto base=RollingHash::generate_base(); RollingHash RH(s,base); using P=pair; map dp; function DP=[&](int l,int r){ if(dp.count(P(l,r))) return dp[P(l,r)]; if(l-1==r) return mint(1); if(l>r) return mint(0); mint ret=1; for(int i=1;l+i<=r-i+1;i++){ if(RH.get(l,l+i)==RH.get(r-i+1,r+1)){ ret+=DP(l+i,r-i); } } return dp[P(l,r)]=ret; }; cout<<(DP(0,n-1))<