#include "bits/stdc++.h" using namespace std; #define DEBUG(x) cout<<#x<<": "< #define vl vector #define vii vector< vector > #define vll vector< vector > #define vs vector #define pii pair #define pis pair #define psi pair #define pll pair const int inf = 1000000001; const ll INF = 1e18 * 2; #define MOD 1000000007 #define mod 1000000009 #define pi 3.14159265358979323846 #define Sp(p) cout< > rh(10010, vector()); vl dp(10010, -1); #define MAXN 10020 //B1, B2:二つの基数 M: modをとる const ll B1 = 100000007; const ll B2 = 103; const ll M = 1000000009; vector Bpower1(MAXN); vector Bpower2(MAXN); vector Bpower_inv1(MAXN); vector Bpower_inv2(MAXN); ll mod_pow(ll x, ll p, ll M) { ll a = 1; while (p) { if (p % 2) a = a*x%M; x = x*x%M; p /= 2; } return a; } ll mod_inverse(ll a, ll m) { return mod_pow(a, m - 2, m); } void build_bpower() { Bpower1[0] = 1; for (int j = 1; j < MAXN; j++) { Bpower1[j] = Bpower1[j - 1] * B1 % M; } Bpower2[0] = 1; for (int j = 1; j < MAXN; j++) { Bpower2[j] = Bpower2[j - 1] * B2 % M; } for (int j = 0; j < MAXN; j++) { Bpower_inv1[j] = mod_inverse(Bpower1[j], M); Bpower_inv2[j] = mod_inverse(Bpower2[j], M); } } //sのハッシュ値を求める //rh[i] = s[i]*(b^(n - i - 1)) + s[i + 1]*(b^(n - i - 2)) + ... + s[n - 1] * b^0; vector rolling_hash(string s) { vector rh(s.size() + 1); rh[s.size()].first = rh[s.size()].second = 0; for (int i = s.size() - 1; i >= 0; i--) { rh[i].first = (rh[i + 1].first + s[i] * Bpower1[s.size() - i - 1]) % M; rh[i].second = (rh[i + 1].second + s[i] * Bpower2[s.size() - i - 1]) % M; } return rh; } //hashに対応する文字列のi文字目からl文字ののハッシュ値を求める //しょっちゅう呼び出す場合は、時間がかかるため本文に直接コピペ pll part(vector hash, int i, int l) { pll h = pll(hash[i].first - hash[i + l].first, hash[i].second - hash[i + l].second); h.first += M; h.second += M; h.first %= M; h.second %= M; h.first = h.first * Bpower_inv1[hash.size() - 1 - i - l] % M; h.second = h.second * Bpower_inv2[hash.size() - 1 - i - l] % M; return h; } ll dfs(int i) { if (dp[i] != -1) { return dp[i]; } if (n % 2 && i == n / 2) { dp[i] = 1; return 1; } ll res = 1; for (int left = i, right = n - 1 - i; left < right; left++, right--) { if (rh[i][left - i] == rh[right][left - i]) { res += dfs(left + 1); res %= MOD; } } dp[i] = res; return res; } int main() { string s; cin >> s; n = s.size(); build_bpower(); auto hash = rolling_hash(s); for (int i = 0; i < n; i++) { for (int j = 0; i + j < n; j++) { pll h1 = pll(hash[i].first - hash[i + j + 1].first, hash[i].second - hash[i + j + 1].second); h1.first += M; h1.second += M; h1.first %= M; h1.second %= M; h1.first = h1.first * Bpower_inv1[hash.size() - 2 - i - j] % M; h1.second = h1.second * Bpower_inv2[hash.size() - 2 - i - j] % M; rh[i].push_back(h1); } } ll ans = dfs(0); cout << ans << endl; }