#include <bits/stdc++.h>
using namespace std;
// macros
typedef long long ll;
typedef long double ld;
typedef pair<int, int> ii;
typedef pair<ll, ll> lll;
typedef tuple<int, int, int> iii;
typedef vector<int> vi;
typedef vector<ii> vii;
typedef vector<iii> viii;
typedef vector<ll> vll;
typedef vector<lll> vlll;
#define REP(a,b,c) for(int a=int(b); a<int(c); a++)
#define RE(a,c) REP(a,0,c)
#define RE1(a,c) REP(a,1,c+1)
#define REI(a,b,c) REP(a,b,c+1)
#define REV(a,b,c) for(int a=int(c-1); a>=int(b); a--)
#define FOR(a,b) for(auto& a : b)
#define all(a) a.begin(), a.end()
#define INF 1e18
#define EPS 1e-9
#define pb push_back
#define popb pop_back
#define fi first
#define se second
#define sz size()
mt19937_64 rng(chrono::steady_clock::now().time_since_epoch().count());
// input
template<class T> void IN(T& x) {cin >> x;}
template<class H, class... T> void IN(H& h, T&... t) {IN(h); IN(t...); }
// output
template<class T1, class T2> void OUT(const pair<T1,T2>& x);
template<class T> void OUT(const vector<T>& x);
template<class T> void OUT(const T& x) {cout << x;}
template<class H, class... T> void OUT(const H& h, const T&... t) {OUT(h); OUT(t...); }
template<class T1, class T2> void OUT(const pair<T1,T2>& x) {OUT(x.fi,' ',x.se);}
template<class T> void OUT(const vector<T>& x) {RE(i,x.size()) OUT(i==0?"":" ",x[i]);}
template<class... T> void OUTL(const T&... t) {OUT(t..., "\n"); }
template<class H> void OUTLS(const H& h) {OUTL(h); }
template<class H, class... T> void OUTLS(const H& h, const T&... t) {OUT(h,' '); OUTLS(t...); }
//===================//
// Added libraries //
//===================//
//===================//
//end added libraries//
//===================//
void program();
int main() {
ios_base::sync_with_stdio(false);
cin.tie(NULL);
cout.tie(NULL);
program();
}
//===================//
// begin program //
//===================//
const int MX = 5e5;
int n;
struct Node {
int nxt[26], sufflink, len;
int cnt=1;
vi adj;
} tree[MX];
string s;
int suf, num;
void initTree() {
num = suf = 2;
tree[1].len = -1; tree[1].sufflink = 1;
tree[2].len = 0; tree[2].sufflink = 1;
tree[1].adj.pb(2);
}
void addLetter(int pos) {
int cur = suf, curLen = 0;
int letter = s[pos]-'a';
while(1) {
curLen = tree[cur].len;
if(pos-1-curLen >= 0 && s[pos-1-curLen] == s[pos])
break;
cur = tree[cur].sufflink;
}
if(tree[cur].nxt[letter]) {
suf = tree[cur].nxt[letter];
tree[suf].cnt++;
return;
}
suf = ++num;
tree[num].len = tree[cur].len+2;
tree[cur].nxt[letter] = suf;
if(tree[num].len == 1) {
tree[num].sufflink = 2;
tree[2].adj.pb(num);
return;
}
while(1) {
cur = tree[cur].sufflink;
curLen = tree[cur].len;
if(pos-1-curLen >= 0 && s[pos-1-curLen] == s[pos]) {
tree[num].sufflink = tree[cur].nxt[letter];
tree[tree[cur].nxt[letter]].adj.pb(num);
break;
}
}
}
ll ans = 0;
void dfs(int u=1) {
FOR(v, tree[u].adj) {
dfs(v);
tree[u].cnt += tree[v].cnt;
}
ans = max(ans, (ll)tree[u].cnt*(ll)tree[u].len);
}
void program() {
IN(s); n=s.sz;
initTree();
RE(i,n) addLetter(i);
dfs();
OUTL(ans);
}
