Problem: Given a string s, find the number of ways to split s to substrings such that if there are k substrings (p1, p2, p3, ..., pk) in partition, then pi = pk - i + 1 for all i (1 ≤ i ≤ k) and k is even.

Since the number of ways can be large, print it modulo 109 + 7.

Input

The only line of input contains a string s (2 ≤ |s| ≤ 106) of even length consisting of lowercase Latin letters. 

Output

Print one integer, the number of ways of partitioning the string modulo 109 + 7.

Examples

Input

abcdcdab


Output

1

Input

abbababababbab


Output

3

Note

In the first case, the only way to partition the string is ab|cd|cd|ab.

In the second case, the string can be partitioned as ab|b|ab|ab|ab|ab|b|ab or ab|b|abab|abab|b|ab or abbab|ab|ab|abbab.

Solution (in JAVA):

Solution:
//package com.company;

import java.io.*;
import java.util.*;

public class Main {
    public static class Task {
        public class EerTree {
            int s, cur; // total of suffix-palindrome nodes, index of current suffix-palindrome
            int N; // final string size, for initiation
            int n; // current string size;
            int[] len;
            int[] suflink;
            int[] diff;
            int[] slink;
            int[][] next;
            int[] string;
            int[] quicklink;
            int[] operations;
            int[] dp;
            int[] ans;
            int operationIndex;
            public EerTree(int N) {
                this.N = N;
                len = new int[N + 2];
                suflink = new int[N + 2];
                diff = new int[N + 2];
                slink = new int[N + 2];
                quicklink = new int[N + 2];
                dp = new int[N + 2];
                ans = new int[N + 2];
                next = new int[N + 2][26];
                string = new int[N];
                for (int i = 0; i < N + 2; i++) {
                    Arrays.fill(next[i], -1);
                }
                len[0] = -1;
                cur = 0;
                s = 2;
                operations = new int[N + 2];
            }

            int getPrevMatch(int cur, int index) {
                if (index - len[cur] - 1 < 0) {
                    cur = suflink[cur];
                }
                while (true) {
                    if (string[index - len[cur] - 1] == string[index]) return cur;
                    if (string[index - len[suflink[cur]] - 1] == string[index]) return suflink[cur];
                    cur = quicklink[cur];
                }
            }

            void insert(int c) {
                string[n] = c;
                operations[operationIndex] = 2 * cur; // to save space ...
                operationIndex++;
                cur = getPrevMatch(cur, n);
                if (next[cur][c] != -1) {
                    cur = next[cur][c];
                } else {
                    operations[operationIndex - 1] |= 1;
                    next[cur][c] = s;
                    len[s] = len[cur] + 2;
                    if (len[s] == 1) {
                        suflink[s] = diff[s] = slink[s] = quicklink[s] = 1;
                    } else {
                        suflink[s] = next[getPrevMatch(suflink[cur], n)][c];
                        diff[s] = len[s] - len[suflink[s]];
                        if (diff[s] == diff[suflink[s]]) {
                            slink[s] = slink[suflink[s]];
                        } else {
                            slink[s] = suflink[s];
                        }
                        if (string[n - len[suflink[s]]] == string[n - len[suflink[suflink[s]]]]) {
                            quicklink[s] = quicklink[suflink[s]];
                        } else {
                            quicklink[s] = suflink[suflink[s]];
                        }
                    }
                    cur = s++;
                }
                n++;
            }

            void pop() {
                operationIndex--;
                int cur = operations[operationIndex] / 2;
                int index = operationIndex;
                int c = string[index];
                if (operations[operationIndex] % 2 != 0) {
                    int rcur = getPrevMatch(cur, index);
                    next[rcur][c] = -1;
                    s--;
                    suflink[s] = diff[s] = slink[s] = quicklink[s] = len[s] = 0;
                }
                this.cur = cur;
                n--;
            }

            int iter(int[] tmpstr) {
                ans[0] = 1;
                for (int i = 1; i <= string.length; i++) {
                    insert(tmpstr[i - 1]);
                    pop();
                    insert(tmpstr[i - 1]);
                    for (int j = cur; j > 1; j = slink[j]) {
                        dp[j] = ans[i - len[slink[j]] - diff[j]];
                        if (diff[j] == diff[suflink[j]]) {
                            dp[j] = add(dp[j], dp[suflink[j]]);
                        }
                        ans[i] = add(ans[i], dp[j]);
                    }
                    if (i % 2 != 0) ans[i] = 0;
                }
                return ans[string.length];
            }
        }
        int mod = 1_000_000_007;
        int add(int a, int b) {
            int c = a + b;
            if (c >= mod) return c - mod;
            if (c < 0) return c + mod;
            return c;
        }

        public void solve(Scanner sc, PrintWriter pw) throws IOException {
            String s = sc.next();
            int[] string = new int[s.length()];
            for (int i = 0; i < s.length() / 2; i++) {
                string[i * 2] = s.charAt(i) - 'a';
                string[i * 2 + 1] = s.charAt(s.length() - i - 1) - 'a';
            }
            EerTree eerTree = new EerTree(string.length);
            pw.println(eerTree.iter(string));
        }
    }
    static long TIME_START, TIME_END;
    public static void main(String[] args) throws IOException {
        Scanner sc = new Scanner(System.in);
//        Scanner sc = new Scanner(new FileInputStream("joker.in"));
        PrintWriter pw = new PrintWriter(new BufferedOutputStream(System.out));
//        PrintWriter pw = new PrintWriter(new FileOutputStream("joker.out"));

        Runtime runtime = Runtime.getRuntime();
        long usedMemoryBefore = runtime.totalMemory() - runtime.freeMemory();
        TIME_START = System.currentTimeMillis();
        Task t = new Task();
        t.solve(sc, pw);
        TIME_END = System.currentTimeMillis();
        long usedMemoryAfter = runtime.totalMemory() - runtime.freeMemory();
        pw.close();
        System.err.println("Memory increased: " + (usedMemoryAfter - usedMemoryBefore) / 1000000);
        System.err.println("Time used: " + (TIME_END - TIME_START) + ".");
    }
    static class Scanner {
        StringTokenizer st;
        BufferedReader br;
        public Scanner(InputStream s) {
            br = new BufferedReader(new InputStreamReader(s));
        }
        public Scanner(FileReader s) throws FileNotFoundException {
            br = new BufferedReader(s);
        }
        public String next() throws IOException {
            while (st == null || !st.hasMoreTokens())
                st = new StringTokenizer(br.readLine());
            return st.nextToken();
        }
        public int nextInt() throws IOException {
            return Integer.parseInt(next());
        }
        public long nextLong() throws IOException {
            return Long.parseLong(next());
        }
        public String nextLine() throws IOException {
            return br.readLine();
        }
        public double nextDouble() throws IOException {
            return Double.parseDouble(next());
        }
        public boolean ready() throws IOException {
            return br.ready();
        }
    }
}