#include <bits/stdc++.h>
#define GET_MACRO(_1,_2,_3,_4,_5,_6,_7,_8,NAME,...) NAME
#define pr(...) cerr<< GET_MACRO(__VA_ARGS__,pr8,pr7,pr6,pr5,pr4,pr3,pr2,pr1)(__VA_ARGS__) <<endl
#define pr1(a) (#a)<<"="<<(a)<<" "
#define pr2(a,b) pr1(a)<<pr1(b)
#define pr3(a,b,c) pr1(a)<<pr2(b,c)
#define pr4(a,b,c,d) pr1(a)<<pr3(b,c,d)
#define pr5(a,b,c,d,e) pr1(a)<<pr4(b,c,d,e)
#define pr6(a,b,c,d,e,f) pr1(a)<<pr5(b,c,d,e,f)
#define pr7(a,b,c,d,e,f,g) pr1(a)<<pr6(b,c,d,e,f,g)
#define pr8(a,b,c,d,e,f,g,h) pr1(a)<<pr7(b,c,d,e,f,g,h)
using namespace std;
using Int = long long;
using _int = int;
using ll = long long;
using Double = long double;
const Int INF = (1LL<<55)+1e9; // ~ 3.6 * 1e16
const Int mod = (1e9)+7;
const Double EPS = 1e-8;
const Double PI = 6.0 * asin((Double)0.5);
using P = pair<Int,Int>;
using T = tuple<Int,Int,Int>;
template<class T> T Max(T &a,T b){return a=max(a,b);}
template<class T> T Min(T &a,T b){return a=min(a,b);}
template<class T1, class T2> ostream& operator<<(ostream& o,pair<T1,T2> p){return o<<"("<<p.first<<","<<p.second<<")";}
template<class T1, class T2, class T3> ostream& operator<<(ostream& o,tuple<T1,T2,T3> t){
  return o<<"("<<get<0>(t)<<","<<get<1>(t)<<","<<get<2>(t)<<")";}
template<class T1, class T2> istream& operator>>(istream& i,pair<T1,T2> &p){return i>>p.first>>p.second;}
template<class T> ostream& operator<<(ostream& o,vector<T> &a){Int i=0;for(T t:a)o<<(i++?" ":"")<<t;return o;}
template<class T> istream& operator>>(istream& i,vector<T> &a){for(T &t:a)i>>t;return i;}
template<class T>void prArr(T a,string s=" "){Int i=0;for(auto t:a)cout<<(i++?s:"")<<t;cout<<endl;}

_int used[2001][2001];
_int mem[2001][2001];
vector<vector<Int> >Idx(30);
string s;
Int dfs(Int l, Int r){
  //pr(l, r);
  if(l > r) return 1;
  if(l == r) return 2;
  if(used[l][r]++) return mem[l][r];

  Int res = 1;
  for(Int i=0;i<26;i++){
    Int idxl = lower_bound(Idx[i].begin(), Idx[i].end(), l) - Idx[i].begin();
    Int idxr = upper_bound(Idx[i].begin(), Idx[i].end(), r) - Idx[i].begin();
    idxr--;
    
    if(idxl >= (int)Idx[i].size() || idxr >=(int)Idx[i].size()) continue;
    if(idxl < 0 || idxr < 0) continue;
    int nl = Idx[i][idxl];
    int nr = Idx[i][idxr];
    if((nl > nr)) continue;
    if(!(l <= nl && nr <= r)) continue;
    if(s[nl] != i + 'a' || s[nr] != i + 'a') continue;
    res = (res + 1) % mod;
    if(nl != nr) res = (res + dfs(nl+1, nr-1)) % mod;
  }
  return mem[l][r] = res;
}

signed main(){
  srand((unsigned)time(NULL));
  cin.tie(0);
  ios_base::sync_with_stdio(0);
  cout << fixed << setprecision(12);

  cin>>s;
  int n = s.size();
  for(Int i=0;i<(Int)s.size();i++) Idx[s[i] - 'a'].push_back(i);

  int ans = 0;
  for(Int i=0;i<26;i++){
    Int idxl = lower_bound(Idx[i].begin(), Idx[i].end(), 0) - Idx[i].begin();
    Int idxr = upper_bound(Idx[i].begin(), Idx[i].end(), n-1) - Idx[i].begin();
    idxr--;
    if(idxl >= (int)Idx[i].size() || idxr >=(int)Idx[i].size()) continue;
    if(idxl < 0 || idxr < 0) continue;
    
    int nl = Idx[i][idxl];
    int nr = Idx[i][idxr];
    
    if(nl >= n || nr >= n) continue;
    if(nl < 0 || nr < 0) continue;
    if(s[nl] != i + 'a' || s[nr] != i + 'a') continue;    
    //pr(char(i+'a'), nl, nr,dfs(nl+1, nr-1));
    ans = (ans+1)%mod;
    if(nl != nr) ans = (ans + dfs(nl+1, nr-1)) % mod;
  } 
  cout<<ans<<endl;
  return 0;
}



Measured memory_bytes: 29000