#include <bits/stdc++.h>
using namespace std;
#define ll long long
#define pb push_back
#define ff first
#define ss second
#define all(s) s.begin(),s.end()
#define rall(s) s.rbegin(),s.rend()
struct Node{
ll nxt[26],sufflink;
ll len,cnt;
vector<ll>edges;
}tree[300005];
string s;
ll suf,num,ans=0;
void init(){
num=2,suf=2;
tree[1].len=-1; tree[1].sufflink=1;
tree[2].len=0; tree[2].sufflink=1;
tree[1].edges.pb(2);
}
void add(ll pos){
ll cur=suf,cur_len=0;
ll x=s[pos]-'a';
while(true){
cur_len=tree[cur].len;
if(pos-1-cur_len>-1&&s[pos-1-cur_len]==s[pos]) break;
cur=tree[cur].sufflink;
}
if(tree[cur].nxt[x]!=0){
suf=tree[cur].nxt[x];
tree[suf].cnt++;
return;
}
suf=++num;
tree[num].len=tree[cur].len+2;
tree[num].cnt=1;
tree[cur].nxt[x]=num;
if(tree[num].len==1){
tree[num].sufflink=2;
tree[2].edges.pb(num);
return;
}
while(true){
cur=tree[cur].sufflink;
cur_len=tree[cur].len;
if(pos-1-cur_len>-1&&s[pos-1-cur_len]==s[pos]){
tree[num].sufflink=tree[cur].nxt[x];
tree[tree[cur].nxt[x]].edges.pb(num);
break;
}
}
}
void dfs(ll i){
for(ll j:tree[i].edges){
dfs(j);
tree[i].cnt+=tree[j].cnt;
}
ans=max(ans,tree[i].len*tree[i].cnt);
}
int main(){
ios_base::sync_with_stdio(false); cin.tie(0); cout.tie(0);
cin>>s;
init();
for(ll i=0;i<s.size();i++){
add(i);
}
dfs(1);
cout<<ans;
}
