#include <iostream>
#include <algorithm>
#include <cstring>

typedef long long ll;
typedef double lf;

// #define DEBUG 1
struct IO
{
    #define MAXSIZE (1 << 20)
    #define isdigit(x) (x >= '0' && x <= '9')
    char buf[MAXSIZE], *p1, *p2;
    char pbuf[MAXSIZE], *pp;
    #if DEBUG
    #else
    IO() : p1(buf), p2(buf), pp(pbuf) {}
    ~IO() {fwrite(pbuf, 1, pp - pbuf, stdout);}
    #endif
    #define gc() (p1 == p2 && (p2 = (p1 = buf) + fread(buf, 1, MAXSIZE, stdin), p1 == p2) ? ' ' : *p1++)
    #define blank(x) (x == ' ' || x == '\n' || x == '\r' || x == '\t')

    template <typename T>
    void Read(T &x)
    {
        #if DEBUG
        std::cin >> x;
        #else
        bool sign = 0; char ch = gc(); x = 0;
        for (; !isdigit(ch); ch = gc())
            if (ch == '-') sign = 1;
        for (; isdigit(ch); ch = gc()) x = x * 10 + (ch ^ 48);
        if (sign) x = -x;
        #endif
    }
    void Read(char *s)
    {
        #if DEBUG
        std::cin >> s;
        #else
        char ch = gc();
        for (; blank(ch); ch = gc());
        for (; !blank(ch); ch = gc()) *s++ = ch;
        *s = 0;
        #endif
    }
    void Read(char &c) {for (c = gc(); blank(c); c = gc());}

    void Push(const char &c)
    {
        #if DEBUG
        putchar(c);
        #else
        if (pp - pbuf == MAXSIZE) fwrite(pbuf, 1, MAXSIZE, stdout), pp = pbuf;
        *pp++ = c;
        #endif
    }
    template <typename T>
    void Write(T x)
    {
        if (x < 0) x = -x, Push('-');
        static T sta[35];
        int top = 0;
        do sta[top++] = x % 10, x /= 10; while (x);
        while (top) Push(sta[--top] ^ 48);
    }
    template <typename T>
    void Write(T x, char lst) {Write(x), Push(lst);}
} IO;
#define Read(x) IO.Read(x)
#define Write(x, y) IO.Write(x, y)
#define Put(x) IO.Push(x)

using namespace std;

const int MAXN = 1e6 + 10;

int n;
char s[MAXN];

int tr[MAXN][26], fail[MAXN], len[MAXN], tot, lst, cnt[MAXN];
inline void PAM_Init() {len[0] = 0, fail[0] = 1, len[1] = -1, tot = 1, lst = 0;}
inline int FindFail(int x, int i)
{
    while (s[i] != s[i - len[x] - 1]) x = fail[x];
    return x;
}
inline void PAM_Extend(int i)
{
    int c = s[i] - 'a', cur = FindFail(lst, i);
    if (!tr[cur][c])
    {
        tr[cur][c] = ++tot, len[tot] = len[cur] + 2;
        if (cur == 1) fail[tot] = 0;
        else fail[tot] = tr[FindFail(fail[cur], i)][c];
    }
    lst = tr[cur][c], cnt[lst]++;
}

int main()
{
    #if DEBUG
    #else
    ios::sync_with_stdio(0), cin.tie(0);
    #endif
    Read(s + 1), n = strlen(s + 1);
    PAM_Init();
    for (int i = 1; i <= n; i++) PAM_Extend(i);
    for (int i = tot; i >= 2; i--) cnt[fail[i]] += cnt[i];
    ll ans = 0;
    for (int i = 2; i <= tot; i++) ans = max(ans, (ll)cnt[i] * len[i] * len[i]);
    cout << ans << '\n';
    return 0;
}