#include <bits/stdc++.h>
#define ull unsigned long long
#define ll long long
#define pb push_back
#define mp make_pair
#define fast ios_base::sync_with_stdio(false); cin.tie(NULL)
#define filein freopen("input.txt","r",stdin)
#define fileout freopen("output.txt","w",stdout)
using namespace std;
const ll mx=300009;
ll nxt[mx][26];
ll len[mx],link[mx];
ll node,t;
string str;
void pre()
{
len[1]=-1,len[2]=0;
link[1]=link[2]=1;
node=t=2;
}
ll cal[mx];
void add(ll p)
{
while(str[p-len[t]-1]!=str[p]) t=link[t];
ll x=link[t];
while(str[p-len[x]-1]!=str[p]) x=link[x];
ll c=str[p]-'a';
if(nxt[t][c]==false)
{
nxt[t][c]=++node;
len[node]=len[t]+2;
link[node]=(len[node]==1)? 2: nxt[x][c];
}
t=nxt[t][c] ;
cal[node]++;
}
int main()
{
cin>>str;
pre();
for(ll i=0;i<(int)str.size();i++) add(i);
for(ll i=node;i>=3;i--) cal[link[i]]+=cal[i];
ll ans=-1;
for(ll i=3;i<=node;i++)
{
ans=max(ans,len[i]*cal[i]);
}
cout<<ans<<endl;
}
