#include<bits/stdc++.h>
using namespace std;
#define ll long long
#define db double
#define ld long double
#define pii pair<int,int>
#define pdd pair<db,db> 
#define fi first
#define se second
#define pb push_back
#define eb emplace_back
//cout<<setiosflags(ios::fixed)<<setprecision(K);
const int dx[4]={1,-1,0,0};
const int dy[4]={0,0,1,-1};
const double eps=1e-9; 
const double PI=acos(-1.0);
const int inf=1e9+7;
const int mod=998244353;
const int N=2e5+10,M=N<<1;

struct PAM {
    static constexpr int ALPHABET_SIZE = 28;
    struct Node {
        int len;
        int link;
        int cnt;
        std::array<int, ALPHABET_SIZE> next;
        Node() : len{}, link{}, cnt{}, next{} {}
    };
    std::vector<Node> t;
    int suff;
    std::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, char offset = 'a') {
        int pos = s.size();
        s += c;
        int let = c - offset;
        int cur = suff, curlen = 0;
        while (true) {
            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) {
            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 size() {
        return t.size();
    }
};

void solve(){
    string s;
    cin>>s;
    PAM pam;
    vector<int>x;
    for(auto c:s){
        pam.add(c);
        x.push_back(pam.suff);
    }

    int n=pam.size();
    vector<int>f(n);
    for(auto v:x) f[v]++;
    vector<vector<int>>adj(n);
    
    for(int i=2;i<n;i++){
        adj[pam.link(i)].push_back(i);
    }

    ll ans=0;
    auto dfs=[&](auto self,int x) -> void {
        for(auto y:adj[x]){
            self(self,y);
            f[x]+=f[y];
        }
        ans=max(ans,1ll*pam.len(x)*pam.len(x)*f[x]);
    };
    dfs(dfs,1);
    cout<<ans<<'\n';
}

signed main(){
    ios::sync_with_stdio(false);
    cin.tie(0);cout.tie(0);
    int T=1;
    //cin>>T;
    while(T--){
        solve();
    }
    return 0;
}