#include<iostream>
#include<array>
#include<cassert>
#include<vector>
struct PalinTree{
static int constexpr MIN='a',CNT=26;
using Idx=int;
static Idx constexpr NONE=-1;
struct Node{
std::array<Idx,CNT> c; // children
Idx link; // suffix link
int len;
// will be used to store number of occurences in the string
int cnt;
Node():link(0x12345678),len(0x12345678),cnt(0){
for(Idx& i:c)i=NONE;
}
};
std::vector<Node> d;
static Idx constexpr ZERO=0, // node coer to emt string
NEG=1; // node coer to the "len = -1" string
template<class Fn>
Idx newnode(Fn f){
auto n=(Idx)d.size();
d.push_back({});
f(d.back());
return n;
}
template<class Fn>
Idx child(Idx a,char c,
Fn f // used in case a new node is constructed
// void(Node&)
){
c-=MIN;
if(d[a].c[c]<0){
Idx ans=newnode(f);
d[a].c[c]=ans;
return ans;
}
return d[a].c[c];
}
// std::string s;
PalinTree(std::string const s):
d(2)
// ,s(std::move(_s))
{
d[ZERO].link=NEG;
d[ZERO].len=0;
d[NEG].len=-1;
Idx n=ZERO; // current node
for(unsigned i=0;i<s.size();++i){
char c=s[i];
while(true){
int j=i-d[n].len;
if(j!=0&&s[j-1]==c){
int newlen=d[n].len+2;
Idx oldlink=d[n].link;
n=child(n,c,[&](Node& z){
z.len=newlen;
if(newlen==1)
z.link=ZERO;
else{
Idx l=oldlink;
while(c!=s[i-d[l].len-1])
l=d[l].link;
z.link=d[l].c[c-MIN];
assert(z.link!=NONE);
}
});
break;
}
n=d[n].link;
}
++d[n].cnt;
}
// accumulate cnt by link edge
std::vector<Idx> ns; // list of nodes sorted by order
ns.reserve(d.size());
ns.push_back((Idx)NEG);
ns.push_back((Idx)ZERO);
for(unsigned i=0;i<d.size();++i){
for(Idx c:d[ns[i]].c)
if(c>=0)
ns.push_back(c);
}
assert(ns.size()==d.size());
for(unsigned i=d.size()-1;i;--i){
int n=ns[i];
d[d[n].link].cnt+=d[n].cnt;
}
}
};
int main(){
std::ios::sync_with_stdio(0);std::cin.tie(0);
std::string s;std::cin>>s;
PalinTree t(s);
int64_t ans=0;
for(unsigned i=2;i<t.d.size();++i)
ans=std::max(ans,(int64_t)t.d[i].len*t.d[i].cnt);
std::cout<<ans<<'\n';
}
