#include <bits/stdc++.h>
using namespace std;
#define print(arr) for(auto& x:arr)cout<<x<<" ";cout<<"\n"
#define watch(x) cout<<#x<<"="<<x<<"\n"
#define all(x) x.begin(), x.end()
#define sz(x) ((int) x.size())
typedef long long ll;
typedef vector<ll> vl;
typedef vector<int> vi;
typedef pair<int, int> ii;
typedef vector<ii> vii;
const int alpha = 26;
const char fc = 'a';
struct Node{
int next[alpha];
int len,link,dep,cnt;
};
struct PalindromeTree{
vector<Node> tree;
string s;
int len,n;
int size; // node 1 - root with len -1, node 2 - root with len 0
int suff; // max suffix palindrome
bool addLetter(int pos){
int cur=suff,curlen=0;
int let=s[pos]-fc;
while(true){
curlen=tree[cur].len;
if(pos-1-curlen>=0 && s[pos-1-curlen]==s[pos])break;
cur=tree[cur].link;
}
if(tree[cur].next[let]){
suff=tree[cur].next[let];
tree[suff].cnt++;
return false;
}
size++;
suff=size;
tree[size].len=tree[cur].len+2;
tree[cur].next[let]=size;
tree[size].cnt=1;
if(tree[size].len==1){
tree[size].link=2;
tree[size].dep=1;
return true;
}
while(true){
cur=tree[cur].link;
curlen=tree[cur].len;
if(pos-1-curlen>=0 && s[pos-1-curlen]==s[pos]){
tree[size].link=tree[cur].next[let];
break;
}
}
tree[size].dep=1+tree[tree[size].link].dep;
return true;
}
void build(string s2, int n){
tree.assign(n+4,Node());
tree[1].len=-1;tree[1].link=1;
tree[2].len=0;tree[2].link=1;
size=2;suff=2;s=s2;
for(int i=0;i<n;i++){
addLetter(i);
}
for(int i=size;i>=3;i--){
tree[tree[i].link].cnt+=tree[i].cnt;
}
}
};
int main(){
ios::sync_with_stdio(false);cin.tie(nullptr);
string s;
cin>>s;
PalindromeTree pt;
pt.build(s,sz(s));
ll ans=0;
for(int i=3;i<=pt.size;i++){
ans=max(ans, 1ll*pt.tree[i].len*pt.tree[i].cnt);
// cout<<i<<" "<<pt.tree[i].len<<" "<<pt.tree[i].link<<" "<<pt.tree[i].dep<<" "<<pt.tree[i].cnt<<"\n";
}
cout<<ans<<"\n";
return 0;
}
