#include <bits/stdc++.h>
using namespace std;

typedef long long ll;
const int maxn = 1e6 + 5;

char s[maxn];
int ch[maxn][26], len[maxn], fail[maxn], siz[maxn];
int tot;

void Init()
{
    tot = 1;
    len[0] = -1, fail[0] = 1;
    len[1] = fail[1] = 0;
}

int getf(int x, int i)
{
    while (s[i] != s[i - len[x] - 1]) x = fail[x];
    return x;
}

int main()
{
    ios::sync_with_stdio(false);
    cin.tie(0);

    cin >> s + 1; s[0] = '&';
    int n = strlen(s + 1);

    int lst = 1; Init();
    for (int i = 1; i <= n; i++)
    {
        int fa = getf(lst, i), c = s[i] - 'a';
        if (!ch[fa][c])
        {
            ch[fa][c] = ++tot;
            len[tot] = len[fa] + 2;
            if (fa) fail[tot] = ch[getf(fail[fa], i)][c];
        }
        lst = ch[fa][c]; siz[ch[fa][c]]++;
    }

    ll ans = 0;
    for (int i = tot; i; i--) siz[fail[i]] += siz[i];
    for (int i = 1; i <= tot; i++) ans = max(ans, (ll)len[i] * len[i] * siz[i]);
    cout << ans;
    return 0;
}