#include <bits/stdc++.h>
#define mp make_pair
#define pb push_back
#define pf push_front
#define popb pop_back
#define popf pop_front
#define xx first
#define yy second
#define ff(i,s,f) for(int i=s;i<f;i++)
#define fb(i,s,f) for(int i=(s)-1;i>=f;i--)
#define ffi(i,s,f) for(int i=s;i<=f;i++)
#define fbi(i,s,f) for(int i=s;i>=f;i--)
#define srt(a) sort(a.begin(),a.end());
#define srtg(a,int) sort(a.begin(),a.end(),greater<int>())
#define lb(a,x) lower_bound(a.begin(),a.end(),x)
#define ub(a,x) upper_bound(a.begin(),a.end(),x)
#define fnd(a,x) find(a.begin(),a.end(),x)
#define vstart auto startt=chrono::system_clock::now()
#define vend auto endd=chrono::system_clock::now()
#define vvreme chrono::duration<double> vremee=endd-startt
#define ios ios_base::sync_with_stdio(false); cin.tie(0); cout.tie(0)
using namespace std;
typedef long long ll;
typedef pair<int,int> pii;
typedef pair<ll,ll> pll;
typedef string str;
struct node{
int dje[26];
int be=0,cnt=0,len=0;
};
vector<node> pt;
node prazan;
int tren;
string s;
void addletter(int i){
while(s[i-pt[tren].len-1]!=s[i]){
tren=pt[tren].be;
}
if(pt[tren].dje[s[i]-'a']==0){
pt.push_back(prazan);
pt[tren].dje[s[i]-'a']=pt.size()-1;
}
int len=pt[tren].len+2;
int be=-1;
int ntren=ntren=pt[tren].be;
while(s[i-pt[ntren].len-1]!=s[i]){
ntren=pt[ntren].be;
}
if(ntren==1){
be=2;
}else{
be=ntren;
}
tren=pt[tren].dje[s[i]-'a'];
pt[tren].len=len;
pt[tren].cnt++;
pt[tren].be=be;
}
void init(){
pt.clear();
pt.push_back(prazan);
pt.push_back(prazan);
pt.push_back(prazan);
pt[1].len=-1;
pt[1].be=1;
pt[2].len=0;
pt[2].be=1;
tren=1;
}
void solve(){
cin>>s;
init();
for(int i=0;i<s.size();i++) addletter(i);
for(int i=(int)pt.size()-1;i>=1;i--){
pt[pt[i].be].cnt+=pt[i].cnt;
}
int maxi=-1;
for(int i=1;i<pt.size();i++){
maxi=max(maxi,pt[i].cnt*pt[i].len);
}
cout<<maxi;
}
int main(){
ios;
int t=1;
//cin>>t;
while(t--) solve();
return 0;
}
