#include<bits/stdc++.h>
using namespace std;
#define int long long
const int maxn=3e5+5;
struct node{
int num=0,len,slink,nxt[26];
}tree[maxn];
int ans,lst,cnt=2;
string s;
void add(int p,int c){
while(tree[lst].len==p || (s[p]!=s[p-tree[lst].len-1])) lst=tree[lst].slink;
if(tree[lst].nxt[c]){
lst=tree[lst].nxt[c];
tree[lst].num++;
return;
}
tree[lst].nxt[c]=++cnt;
tree[cnt].len=tree[lst].len+2;
tree[cnt].num++;
if(tree[cnt].len==1){
tree[cnt].slink=2;lst=cnt;
return;
}
lst=tree[lst].slink;
while(tree[lst].len==p || (s[p]!=s[p-tree[lst].len-1])) lst=tree[lst].slink;
tree[cnt].slink=tree[lst].nxt[c];lst=cnt;
}
signed main(){
ios_base::sync_with_stdio(false);
cin.tie(NULL);cout.tie(NULL);
cin >> s;lst=2;
tree[1].slink=tree[2].slink=1;
tree[1].len=-1;tree[2].len=0;
for(int i=0;i<(int)s.length();i++) add(i,s[i]-'a');
for(int i=cnt;i>=2;i--){
tree[tree[i].slink].num+=tree[i].num;
ans=max(ans,tree[i].num*tree[i].len);
}
cout << ans << '\n';
}
