#include <bits/stdc++.h>

using namespace std;

const int N = 5e5 + 5;

int n;
char s[N];
int tot = 1, len[N], fail[N], ch[N][26], siz[N];
long long ans;

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

vector<int> G[N];

void dfs(int u)
{
    for(auto v : G[u])
        if(u != v) dfs(v), siz[u] += siz[v];
    if(len[u] > 0) ans = max(ans, 1ll * siz[u] * len[u] * len[u]);
    return;
}

int main()
{
    ios::sync_with_stdio(false);
    cin.tie(nullptr), cout.tie(nullptr);

    cin >> (s + 1); n = strlen(s + 1);

    fail[0] = fail[1] = 1, len[1] = -1;
    for(int i = 1, x = 0; i <= n; i++)
    {
        x = getfail(x, i);
        if(!ch[x][s[i] - 'a'])
        {
            tot++;
            fail[tot] = ch[getfail(fail[x], i)][s[i] - 'a'];
            ch[x][s[i] - 'a'] = tot;
            len[tot] = len[x] + 2;
        }
        x = ch[x][s[i] - 'a'];
        siz[x]++;
    }
    for(int i = 0; i <= tot; i++) G[fail[i]].push_back(i);
    dfs(1);
    cout << ans << '\n';
    return 0;
}