#include<bits/stdc++.h>
using namespace std;
#ifdef DEBUG
auto& operator <<(auto& o, pair<auto, auto> p) {return o<<"{"<<p.first<<", "<<p.second<<"}";}
auto operator <<(auto& o, auto x)->decltype(x.end(), o) {o<<"{"; for(auto v : x) o<<v<<", "; return o<<"}";}
#define debug(X) cerr<<"["#X"]: "<<X<<endl;
#else
#define debug(X) {}
#endif
int cnt = 0;
struct node
{
vector<node*> edg;
node* sufLink = nullptr;
int idx = 0;
int val = 0;
int sz = -1;
node(node* suf, int s){
idx = cnt++;
sufLink = suf, sz = s;
}
node(){idx = cnt++;}
};
unordered_map<int, node*> sons;
struct palTrie
{
string s;
node Oroot;
node* add(char let, int pos, node* prev)
{
debug(let);
debug(pos);
node* nw = nullptr;
bool e = 0;
while(prev != nullptr)
{
if(pos-1-prev->sz >= 0 && s[pos-1-prev->sz]-'a' == let)
{
if(nw == nullptr)
{
if(sons[prev->idx*30+let] == nullptr)
{
sons[prev->idx*30+let]
= new node(&Oroot, prev->sz + 2);
e = true;
}
nw = sons[prev->idx*30+let];
nw->val++;
if(!e) break;
}
else
{
nw->sufLink = sons[prev->idx*30+let];
break;
}
}
prev = prev->sufLink;
}
if(e)
nw->sufLink->edg.push_back(nw);
return nw;
}
long long res = 0;
int dfs(node* a)
{
int sum = a->val;
for(auto v : a->edg)
sum += dfs(v);
debug(a->sz);
debug(sum);
if(a->sz != -1)
res = max(res, (long long)sum * (long long)(a->sz/2));
return sum;
}
palTrie(string _s)
{
s = _s;
int k = 0;
node* p = &Oroot;
for(auto v : s) p = add(v - 'a', k++, p);
dfs(&Oroot);
}
};
int32_t main()
{
ios_base::sync_with_stdio(false);
cin.tie(0);
cout.tie(0);
string s;
cin>>s;
char g = 'z' + 1;
string t = "";
t += g;
for(auto v : s) {t += v; t += g;}
s = t;
debug(s);
palTrie A(s);
debug(A.res);
cout<<A.res;
}
