#include<bits/stdc++.h>
#define ll long long
#define pii pair<int,int> 
#define fi first
#define se second
using namespace std;
const int N=5e5+10;
int n,len[N],num[N],fail[N];
int ch[N][27],tot=1,siz[N];
char s[N];
vector<int>to[N];
int get(int x,int i)
{
    while(i-len[x]-1<1||s[i-len[x]-1]!=s[i])x=fail[x];
    return x;   
}
ll ans;
void dfs(int u)
{
    // siz[u]=1;
    for(int v:to[u])
    {
        dfs(v);
        siz[u]+=siz[v];
    }
    // cout<<siz[u]<<" "<<len[u]<<endl;
    if(len[u]>0)ans=max(ans,1ll*siz[u]*len[u]*len[u]);
}
int main()
{
    scanf("%s",s+1);
    n=strlen(s+1);
    len[1]=-1;fail[0]=1;
    int now=0;
    for(int i=1;i<=n;i++)
    {
        int c=s[i]-'a'+1;
        now=get(now,i);
        if(!ch[now][c])
        {
            fail[++tot]=ch[get(fail[now],i)][c];
            ch[now][c]=tot;
            len[tot]=len[now]+2;
        }
        now=ch[now][c];
        siz[now]++;
        // cout<<len[now]<<" ";
    }
    for(int i=0;i<=tot;i++)
        if(i!=1)
            to[fail[i]].push_back(i);
    dfs(1);
    printf("%lld\n",ans);
	return 0;
}