#include <algorithm>
#include <vector>
#include <cstdio>
#include <cstring>
#include <iostream>
#define PB push_back
using namespace std;
typedef long long ll;
const int N = 3e5 + 500;
const int INF = 0x3f3f3f3f;
const int ALP = 26;
struct node{
node *ch[ALP], *bk;
int len, cnt;
node(int _len = 0) { len = _len, cnt = 0, bk = 0, memset(ch, 0, sizeof(ch)); }
};
node *n0, *n1;
vector < node* > v;
node* create_eertree(string &s){
n0 = new node(0);
n1 = new node(-1);
n0->bk = n1; n1->bk = n1;
node* cur = n0;
for(int i = 0;i < (int)s.size();i++){
for(;cur->len+1>i||s[i-cur->len-1]!=s[i];cur=cur->bk);
node *rmb = cur->bk;
if(!cur->ch[s[i]-'a'])
cur->ch[s[i]-'a'] = new node(cur->len + 2);
cur = cur->ch[s[i] - 'a']; cur->cnt++;
for(;rmb->len+1>i||s[i-rmb->len-1]!=s[i];rmb=rmb->bk);
if(cur->len == 1)
cur->bk = n0;
else{
if(!rmb->ch[s[i] - 'a'])
rmb->ch[s[i] - 'a'] = new node(rmb->len + 2);
cur->bk = rmb->ch[s[i] - 'a'];
}
}
return n0;
}
bool cmp(node* X, node* Y){
return X->len > Y->len;
}
string s;
void dfs(node* x) {
if(!x) return;
v.PB(x);
for(int i = 0;i < 26;i++)
if(x->ch[i]) dfs(x->ch[i]);
}
int main(){
ios_base::sync_with_stdio(false);
cin.tie(0);
cin >> s;
ll mx = 0;
node* root = create_eertree(s);
dfs(root); dfs(root->bk);
sort(v.begin(), v.end(), cmp);
for(int i = 0;i < (int)v.size();i++){
mx = max(mx, (ll)v[i]->len * v[i]->cnt);
v[i]->bk->cnt += v[i]->cnt;
}
cout << mx << endl;
}
