#include <cstdio>
#include <algorithm>
#include <cstring>
#include <vector>
#include <iostream>
using namespace std;
int n;
char s[1000010];
long long ans;
vector<int>g[1000010];
struct PAM{
    int cnt,len[1000010],fail[1000010],size[1000010],trie[1000010][26];
    PAM(){}
    int getfail(int x,int i){
        while(i-len[x]<=0||s[i-len[x]-1]!=s[i])x=fail[x];
        return x;
    }
    void build(){
        cnt=1;fail[0]=1;fail[1]=-1;len[1]=-1;
        int p=0;
        for(int i=1;i<=n;i++){
            int x=getfail(p,i);
            if(!trie[x][s[i]-'a']){
                fail[++cnt]=trie[getfail(fail[x],i)][s[i]-'a'];
                trie[x][s[i]-'a']=cnt;
                len[cnt]=len[x]+2;
            }
            p=trie[x][s[i]-'a'];size[p]++;
        }
    }
    void dfs(int x){
        for(int v:g[x]){
            dfs(v);size[x]+=size[v];
        }
        if(len[x]>=0)ans=max(ans,1ll*size[x]*len[x]*len[x]);
    }
}pam;
int main(){
    scanf("%s",s+1);n=strlen(s+1);pam.build();
    for(int i=0;i<=pam.cnt;i++)if(~pam.fail[i])g[pam.fail[i]].push_back(i);
    pam.dfs(1);
    printf("%lld\n",ans);
    return 0;
}