#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef vector<int> vi;
typedef vector<vi> vii;
typedef pair<int,int> pi;
typedef vector<pi> pii;
typedef tuple<ll,ll,ll> ti;
typedef vector<ll> li;
typedef vector<li> lii;
#define REP(i,a,b) for(int i=a;i<b;i++)
#define F first
#define S second
#define PB push_back
#define LSOne(s) ((s)&(-s))
ll INF=1000000000000000010;
int inf=1e9+10;
ll M=1e9+7;
struct node{
int sz;
int next[26];
int suf;
};
int n,pos=2,cnt[300002];
string s;
vector<node> a(3000002);
int suff=0;
void letter(int x){
int c=s[x]-'a';
if(a[suff].sz==x)suff=a[suff].suf;
while(suff>0&&s[x-1-a[suff].sz]!=s[x])suff=a[suff].suf;
if(a[suff].next[c]==-1){
a[suff].next[c]=pos;
a[pos].sz=a[suff].sz+2;
while(suff>0&&s[x-1-a[suff].sz]!=s[x])suff=a[suff].suf;
a[pos].suf=suff;
if(a[pos].sz==1)a[pos].suf=1;
cnt[pos]++;
suff=pos;
pos++;
}
else cnt[a[suff].next[c]]++;
}
int main() {
// ios::sync_with_stdio(0);
// cin.tie(0);
cin>>s;
n=s.size();
memset(cnt,0,sizeof(cnt));
REP(i,0,n+2)REP(j,0,26)a[i].next[j]=-1;
a[0].sz=-1;a[0].suf=0;
a[1].sz=0;a[1].suf=0;
REP(i,0,n)letter(i);
priority_queue<pi> pq;
REP(i,2,n+2)pq.push({a[i].sz,i});
int ans=0;
REP(i,0,n){
int x=pq.top().S;
ans=max(ans,a[x].sz*cnt[x]);
REP(j,0,26)if(a[x].next[j]!=-1)cnt[a[x].next[j]]+=cnt[x];
pq.pop();
}
cout<<ans;
}
