#include using namespace std; typedef long long signed int LL; typedef long long unsigned int LU; #define incII(i, l, r) for(int i = (l) ; i <= (r); ++i) #define incID(i, l, r) for(int i = (l) ; i < (r); ++i) #define decII(i, l, r) for(int i = (r) ; i >= (l); --i) #define decID(i, l, r) for(int i = (r) - 1; i >= (l); --i) #define inc(i, n) incID(i, 0, n) #define inc1(i, n) incII(i, 1, n) #define dec(i, n) decID(i, 0, n) #define dec1(i, n) decII(i, 1, n) #define inII(v, l, r) ((l) <= (v) && (v) <= (r)) #define inID(v, l, r) ((l) <= (v) && (v) < (r)) #define PB push_back #define EB emplace_back #define MP make_pair #define FI first #define SE second #define ALL(v) v.begin(), v.end() #define RALL(v) v.rbegin(), v.rend() template bool setmin (T & a, T b) { if(b < a) { a = b; return true; } else { return false; } } template bool setmax (T & a, T b) { if(b > a) { a = b; return true; } else { return false; } } template bool setmineq(T & a, T b) { if(b <= a) { a = b; return true; } else { return false; } } template bool setmaxeq(T & a, T b) { if(b >= a) { a = b; return true; } else { return false; } } LL mo(LL a, LL b) { assert(b > 0); a %= b; if(a < 0) { a += b; } return a; } LL fl(LL a, LL b) { assert(b > 0); return (a > 0 ? a / b : (a - b + 1) / b); } LL ce(LL a, LL b) { assert(b > 0); return (a < 0 ? a / b : (a + b - 1) / b); } #define bit(b, i) (((b) >> (i)) & 1) #define BC __builtin_popcountll #define SC(T, v) static_cast(v) #define SI(v) SC(int, v.size()) #define SL(v) SC( LL, v.size()) #define RF(e, v) for(auto & e: v) #define ei else if #define UR assert(false) // ---- ---- const int M = 5001; bool f[M][M]; LL dp[M], MOD = 1e9 + 7; int main() { string s; cin >> s; int n = SI(s); int h = fl(n, 2); incII(i, 0, h) { int j = n - i; inc1(k, i) { if(! (i + k <= h)) { break; } bool g = (s[i - k] == s[j - k] && s[i + k - 1] == s[j + k - 1]); f[i + k][i - k] = g; if(! g) { break; } } } inc(i, h) { int j = n - i - 1; incII(k, 0, i) { if(! (i + k < h)) { break; } bool g = (s[i - k] == s[j - k] && s[i + k] == s[j + k]); f[i + k + 1][i - k] = g; if(! g) { break; } } } LL ans = 0; dp[0] = 1; incII(i, 0, h) { inc(j, i) { if(f[i][j]) { dp[i] += dp[j]; } } dp[i] %= MOD; ans += dp[i]; } ans %= MOD; cout << ans << endl; return 0; }