using System; using System.Collections.Generic; using System.Linq; using System.IO; using static System.Console; using static System.Convert; using static System.Math; using Pi = Pair; using PL = Pair; //using static System.Globalization.CultureInfo; using System.Text; class Program { public static bool chmin(ref T num, T val) where T : IComparable { if (num.CompareTo(val) == 1) { num = val; return true; } return false; } public static bool chmax(ref T num, T val) where T : IComparable { if (num.CompareTo(val) == -1) { num = val; return true; } return false; } public static void swap(ref T v1, ref T v2) { var t = v2; v2 = v1; v1 = t; } public static void Fail() => Fail("No"); public static void Fail(T s) { WriteLine(s); Console.Out.Close(); Environment.Exit(0); } static void Main(string[] args) { var sw = new StreamWriter(Console.OpenStandardOutput()) { AutoFlush = false }; Console.SetOut(sw); var p = new Program(); for (var i = 1; i > 0; --i) p.Solve(); Console.Out.Flush(); } string str; RollingHash rh; ModInt[] memo; bool[] th; void Solve() { str = ReadLine();rh = new RollingHash(str); memo = new ModInt[str.Length]; th = new bool[str.Length]; WriteLine(dp(0, str.Length - 1)); } ModInt dp(int l,int r) { if (r < l) return 1; if (th[l]) return memo[l]; ModInt calc = 1; int le = l, ri = r; while(le h1[v]==h2[v])) calc += dp(le + 1, ri - 1); le++;ri--; } th[l] = true; return memo[l] = calc; } } public struct ModInt { public const long MOD = (int)1e9 + 7; //public const long MOD = 998244353; public long num { get; set; } public ModInt(long n = 0) { num = n; } private static ModInt[] _fac;//ιšŽδΉ— private static ModInt[] _inv;//逆数 private static ModInt[] _facrev;//1/(i!) public override string ToString() => num.ToString(); public static ModInt operator +(ModInt l, ModInt r) { l.num += r.num; if (l.num >= MOD) l.num -= MOD; return l; } public static ModInt operator -(ModInt l, ModInt r) { l.num -= r.num; if (l.num < 0) l.num += MOD; return l; } public static ModInt operator *(ModInt l, ModInt r) => new ModInt(l.num * r.num % MOD); public static ModInt operator /(ModInt l, ModInt r) => l * Pow(r, MOD - 2); public static implicit operator long(ModInt l) => l.num; public static implicit operator ModInt(long n) { n %= MOD; if (n < 0) n += MOD; return new ModInt(n); } public static ModInt Pow(ModInt m, long n) { if (n == 0) return 1; if (n % 2 == 0) return Pow(m * m, n >> 1); else return Pow(m * m, n >> 1) * m; } public static void CombBuild(int n) { _fac = new ModInt[n + 1]; _facrev = new ModInt[n + 1]; _inv = new ModInt[n + 1]; _inv[1] = 1; _fac[0] = _fac[1] = 1; _facrev[0] = _facrev[1] = 1; for (var i = 2; i <= n; i++) { _fac[i] = _fac[i - 1] * i; _inv[i] = MOD - _inv[MOD % i] * (MOD / i); _facrev[i] = _facrev[i - 1] * _inv[i]; } } public static ModInt Fac(ModInt n) => _fac[n]; public static ModInt Div(ModInt n) => _inv[n]; public static ModInt FacRev(ModInt n) => _facrev[n]; public static ModInt Part(ModInt n, ModInt r) { if (n < r) return 0; return _fac[n] * _facrev[n - r]; } public static ModInt Comb(ModInt n, ModInt r) { if (n < r) return 0; if (n == r) return 1; var calc = _fac[n]; calc = calc * _facrev[r]; calc = calc * _facrev[n - r]; return calc; } } public class RollingHash { public string str { get; } private ulong[][] hashTable; private static ulong[][] pow; private static uint[] bases { get; } public static int BaseCount { get { return bases.Length; } } const ulong MASK30 = (1UL << 30) - 1; const ulong MASK31 = (1UL << 31) - 1; private const ulong MOD = (1UL << 61) - 1; public RollingHash(string str) { this.str = str; hashTable = Enumerable.Repeat(0, BaseCount).Select(_ => new ulong[str.Length + 1]).ToArray(); for (var i = 0; i < BaseCount; i++) for (var j = 1; j <= str.Length; j++) hashTable[i][j] = CalcMod(Mul(hashTable[i][j - 1], bases[i]) + str[j - 1]); } static RollingHash() { var rnd = new Random(); int min = 150, max = int.MaxValue; bases = Enumerable.Repeat(0, 1).Select(_ => (uint)rnd.Next(min, max)).ToArray(); pow = Enumerable.Repeat(0, BaseCount).Select(_ => new ulong[10001]).ToArray(); for (var i = 0; i < BaseCount; i++) pow[i][0] = 1; for (var i = 0; i < BaseCount; i++) for (var j = 1; j < pow[i].Length; j++) pow[i][j] = Mul(pow[i][j - 1], bases[i]); } private static ulong Mul(ulong a,ulong b) { var au = a >> 31; var ad = a & MASK31; var bu = b >> 31; var bd = b & MASK31; var mid = ad * bu + au * bd; var midu = mid >> 30; var midd = (mid & MASK30); return CalcMod(au * bu * 2 + midu + (midd << 31) + ad * bd); } private static ulong CalcMod(ulong val) { val = (val & MOD) + (val >> 61); if (val > MOD) val -= MOD; return val; } public ulong[] GetHash(int l = 0, int r = -1) { if (r < 0) r = str.Length; var h = new ulong[BaseCount]; for (var i = 0; i < BaseCount; i++) h[i] = CalcMod(hashTable[i][r] + MOD * ((1UL << 3) - 1) - Mul(hashTable[i][l], pow[i][r - l])); return h; } } public class Input { public static string read => ReadLine().Trim(); public static int[] ar => read.Split(' ').Select(int.Parse).ToArray(); public static int num => ToInt32(read); public static long[] arL => read.Split(' ').Select(long.Parse).ToArray(); public static long numL => ToInt64(read); public static T[] create(int n, Func f) => Enumerable.Repeat(0, n).Select(f).ToArray(); public static char[][] grid(int h) => create(h, _ => read.ToCharArray()); public static int[] ar1D(int n) => create(n, _ => num); public static long[] arL1D(int n) => create(n, _ => numL); public static string[] strs(int n) => create(n, _ => read); public static int[][] ar2D(int n) => create(n, _ => ar); public static long[][] arL2D(int n) => create(n, _ => arL); public static List[] edge(int n) => create(n, _ => new List()); public static T GetValue(string g) { var t = typeof(T); if (t == typeof(int)) return (T)(object)int.Parse(g); if (t == typeof(long)) return (T)(object)long.Parse(g); if (t == typeof(string)) return (T)(object)g; if (t == typeof(char)) return (T)(object)char.Parse(g); if (t == typeof(double)) return (T)(object)double.Parse(g); if (t == typeof(bool)) return (T)(object)bool.Parse(g); return default(T); } public static void Make(out T1 v1, out T2 v2) { v1 = Next(); v2 = Next(); } public static void Make(out T1 v1, out T2 v2, out T3 v3) { Make(out v1, out v2); v3 = Next(); } public static void Make(out T1 v1, out T2 v2, out T3 v3, out T4 v4) { Make(out v1, out v2, out v3); v4 = Next(); } public static void Make(out T1 v1, out T2 v2, out T3 v3, out T4 v4, out T5 v5) { Make(out v1, out v2, out v3, out v4); v5 = Next(); } public static void Make(out T1 v1, out T2 v2, out T3 v3, out T4 v4, out T5 v5, out T6 v6) { Make(out v1, out v2, out v3, out v4, out v5); v6 = Next(); } private static Queue sc; public static T Next() { sc = sc ?? new Queue(); if (sc.Count == 0) foreach (var item in read.Split(' ')) sc.Enqueue(item); return GetValue(sc.Dequeue()); } public static void Next(ref T val) => val = Next(); public const long Inf = (long)1e18; public const double eps = 1e-6; public const string Alfa = "abcdefghijklmnopqrstuvwxyz"; public const int MOD = 1000000007; } public class Pair : IComparable> { public T1 v1 { get; set; } public T2 v2 { get; set; } public Pair() { v1 = Input.Next(); v2 = Input.Next(); } public Pair(T1 v1, T2 v2) { this.v1 = v1; this.v2 = v2; } public int CompareTo(Pair p) { var c = Comparer.Default.Compare(v1, p.v1); if (c == 0) c = Comparer.Default.Compare(v2, p.v2); return c; } public override string ToString() => $"{v1.ToString()} {v2.ToString()}"; public override bool Equals(object obj) => this == (Pair)obj; public override int GetHashCode() => v1.GetHashCode() ^ v2.GetHashCode(); public static bool operator ==(Pair p1, Pair p2) => p1.CompareTo(p2) == 0; public static bool operator !=(Pair p1, Pair p2) => p1.CompareTo(p2) != 0; public static bool operator >(Pair p1, Pair p2) => p1.CompareTo(p2) == 1; public static bool operator >=(Pair p1, Pair p2) => p1.CompareTo(p2) != -1; public static bool operator <(Pair p1, Pair p2) => p1.CompareTo(p2) == -1; public static bool operator <=(Pair p1, Pair p2) => p1.CompareTo(p2) != 1; } public class Pair : Pair, IComparable> { public T3 v3 { get; set; } public Pair() : base() { v3 = Input.Next(); } public Pair(T1 v1, T2 v2, T3 v3) : base(v1, v2) { this.v3 = v3; } public int CompareTo(Pair p) { var c = base.CompareTo(p); if (c == 0) c = Comparer.Default.Compare(v3, p.v3); return c; } public override string ToString() => $"{base.ToString()} {v3.ToString()}"; }