#include <bits/stdc++.h>
using namespace std;
using ll = long long;
struct PAM {
    static constexpr int ALPHABET_SIZE = 26;
    struct Node {
        int len;
        int link;
        int cnt;
        array<int, ALPHABET_SIZE> next;
        Node() : len{}, link{}, cnt{}, next{} {}
    };
    vector<Node> t;
    int suff;
    string s;
    PAM() {
        init();
    }
    void init() {
        t.assign(2, Node());
        t[0].len = -1;
        suff = 1;
        s.clear();
    }
    int newNode() {
        t.emplace_back();
        return t.size() - 1;
    }
    bool add(char c) {
        int pos = s.size();
        s += c;
        int let = c - 'a';
        int cur = suff, curlen = 0;
        while(true) {//getfail
            curlen = t[cur].len;
            if(pos - 1 - curlen >= 0 && s[pos - 1 - curlen] == s[pos]) {
                break;
            }
            cur = t[cur].link;
        }
        if(t[cur].next[let]) {
            suff = t[cur].next[let];
            return false;
        }
        int num = newNode();
        suff = num;
        t[num].len = t[cur].len + 2;
        t[cur].next[let] = num;
        if(t[num].len == 1) {
            t[num].link = 1;
            t[num].cnt = 1;
            return true;
        }
        while(true) {//getfail
            cur = t[cur].link;
            curlen = t[cur].len;
            if (pos - 1 - curlen >= 0 && s[pos - 1 - curlen] == s[pos]) {
                t[num].link = t[cur].next[let];
                break;
            }
        }
        t[num].cnt = 1 + t[t[num].link].cnt;
        return true;
    }
    int next(int p, int x) {
        return t[p].next[x];
    }
    int link(int p) {
        return t[p].link;
    }
    int len(int p) {
        return t[p].len;
    }
    int cnt(int p) {
        return t[p].cnt;
    }
    int size() {
        return t.size();
    }
};
void solve()
{
    string s;
    cin>>s;
    PAM pam;
    vector<int> ends;
    for(char ch: s)
    {
        pam.add(ch);
        ends.push_back(pam.suff);
    }
    vector<int> f(pam.size());
    for(int v: ends)
        f[v]++;
    vector adj(pam.size(),vector<int>());
    for(int i=2;i<pam.size();i++)
        adj[pam.link(i)].push_back(i);
    ll ans=0;
    auto dfs=[&](auto &&dfs,int u)->void
    {
        for(int v: adj[u])
        {
            dfs(dfs,v);
            f[u]+=f[v];
        }
        ans=max(ans,1LL*pam.len(u)*pam.len(u)*f[u]);
    };
    dfs(dfs,1);
    cout<<ans<<"\n";
}
int main()
{
    ios::sync_with_stdio(false),cin.tie(0),cout.tie(0);
    cout<<fixed<<setprecision(3);
    int _=1;
    // cin>>_;
    while(_--)
        solve();
    return 0;
}