#include<bits/stdc++.h>
using namespace std;
const int MAXN=1e6+5;
struct node
{
int nex[26],len,sufflink,last,child,cnt;
};
node ptree[MAXN];
char c[MAXN];
int cchar=0,cnt=2,suff=2,ans[MAXN];
void ins(char w)
{
c[++cchar]=w;
int v=w-'a';
while(true)
{
if(c[cchar-ptree[suff].len-1]==w) break;
else suff=ptree[suff].sufflink;
}
int sus=suff;
if(!ptree[suff].nex[v]) ptree[suff].nex[v]=++cnt;
suff=ptree[suff].nex[v],ptree[suff].child=sus;
ptree[suff].len=ptree[sus].len+2;
ptree[suff].last=v,ptree[suff].cnt++;
if(ptree[suff].len==1)
{
ptree[suff].sufflink=2;
return ;
}
while(true)
{
sus=ptree[sus].sufflink;
if(c[cchar-ptree[sus].len-1]==w) break;
}
ptree[suff].sufflink=ptree[sus].nex[v];
}
int main()
{
ios::sync_with_stdio(0);
cin.tie(0);
cout.tie(0);
string s;
cin>>s;
int n=s.length();
ptree[1].len=-1,ptree[2].sufflink=1;
for(auto v:s) ins(v);
long long ans=0;
for(int i=cnt;i;i--)
{
ans=max(ans,(long long)ptree[i].len*ptree[i].cnt);
ptree[ptree[i].sufflink].cnt+=ptree[i].cnt;
}
cout<<ans;
}
