#include "bits/stdc++.h" using namespace std; #define FOR(i,j,k) for(int (i)=(j);(i)<(int)(k);++(i)) #define rep(i,j) FOR(i,0,j) #define each(x,y) for(auto &(x):(y)) #define mp make_pair #define mt make_tuple #define all(x) (x).begin(),(x).end() #define debug(x) cout<<#x<<": "<<(x)< pii; typedef vector vi; typedef vector vll; struct RollingHash { static const int C = 31, C2 = 29, P = 1000000007, P2 = 1000000009; int _n; vector pw, pw2, hs, hs2; RollingHash() {} RollingHash(const string &st) :_n((int)st.size()), pw(_n + 1), pw2(_n + 1), hs(_n + 1), hs2(_n + 1) { pw[0] = pw2[0] = 1; rep(i, _n) { pw[i + 1] = (pw[i] * C) % P; pw2[i + 1] = (pw2[i] * C2) % P2; hs[i + 1] = (C*hs[i] + st[i]) % P; hs2[i + 1] = (C2*hs2[i] + st[i]) % P2; } } // [l, r) pii getHash(int l, int r) { int res, res2; res = (hs[r] - hs[l] * pw[r - l]) % P; res2 = (hs2[r] - hs2[l] * pw2[r - l]) % P2; if (res < 0)res += P; if (res2 < 0)res2 += P2; return mp(res, res2); } }; template class ModInt { public: ModInt() :value(0) {} ModInt(long long val) :value((int)(val<0 ? MOD + val%MOD : val%MOD)) { } ModInt& operator+=(ModInt that) { value = value + that.value; if (value >= MOD)value -= MOD; return *this; } ModInt& operator-=(ModInt that) { value -= that.value; if (value<0)value += MOD; return *this; } ModInt& operator*=(ModInt that) { value = (int)((long long)value * that.value % MOD); return *this; } ModInt &operator/=(ModInt that) { return *this *= that.inverse(); } ModInt operator+(ModInt that) const { return ModInt(*this) += that; } ModInt operator-(ModInt that) const { return ModInt(*this) -= that; } ModInt operator*(ModInt that) const { return ModInt(*this) *= that; } ModInt operator/(ModInt that) const { return ModInt(*this) /= that; } ModInt pow(long long k) const { if (value == 0)return 0; ModInt n = *this, res = 1; while (k) { if (k & 1)res *= n; n *= n; k >>= 1; } return res; } ModInt inverse() const { long long a = value, b = MOD, u = 1, v = 0; while (b) { long long t = a / b; a -= t * b; swap(a, b); u -= t * v; swap(u, v); } return ModInt(u); } int toi() const { return value; } private: int value; }; typedef ModInt<1000000007> mint; ostream& operator<<(ostream& os, const mint& x) { os << x.toi(); return os; } int main(){ ios::sync_with_stdio(false); cin.tie(0); string S; cin >> S; int N = sz(S); vector dp(N); dp[0] = 1; RollingHash rh = RollingHash(S); rep(i, N / 2) { for (int j = i + 1; j <= N / 2; ++j) { if (rh.getHash(i, j) == rh.getHash(N - j, N - i)) { dp[j] += dp[i]; } } } mint ans = accumulate(all(dp), mint()); cout << ans << endl; }