#include <bits/stdc++.h>
using namespace std;
#define INF 1<<30
#define endl '\n'
#define maxn 100005
#define tc printf("Case %d: ", cs)
#define tcn printf("Case %d:\n", cs);
#define FASTIO ios_base::sync_with_stdio(false), cin.tie(0), cout.tie(0);
typedef long long ll;
const double PI = acos(-1.0);
#define dbg1(x) cerr << #x << " = " << x << endl;
#define dbg2(x, y) cerr << #x << " = " << x << ", " << #y << " = " << y << endl;
#define dbg3(x, y, z) cerr << #x << " = " << x << ", " << #y << " = " << y << ", " << #z << " = " << z << endl;
#define dbg4(w,x, y, z) cerr << #w << " = " << w << ", " <<#x << " = " << x << ", " << #y << " = " << y << ", " << #z << " = " << z << endl;
template < typename F, typename S >
ostream& operator << ( ostream& os, const pair< F, S > & p ) {
return os << "(" << p.first << ", " << p.second << ")";
}
template < typename T >
ostream &operator << ( ostream & os, const vector< T > &v ) {
os << "{";
for (auto it = v.begin(); it != v.end(); ++it) {
if ( it != v.begin() ) os << ", ";
os << *it;
}
return os << "}";
}
template < typename T >
ostream &operator << ( ostream & os, const set< T > &v ) {
os << "[";
for (auto it = v.begin(); it != v.end(); ++it) {
if ( it != v.begin()) os << ", ";
os << *it;
}
return os << "]";
}
template < typename F, typename S >
ostream &operator << ( ostream & os, const map< F, S > &v ) {
os << "[";
for (auto it = v.begin(); it != v.end(); ++it) {
if ( it != v.begin() ) os << ", ";
os << it -> first << " = " << it -> second ;
}
return os << "]";
}
#define dbg(args...) do {cerr << #args << " : "; faltu(args); } while(0)
clock_t tStart = clock();
#define timeStamp dbg("Execution Time: ", (double)(clock() - tStart)/CLOCKS_PER_SEC)
void faltu () { cerr << endl; }
template <typename T>
void faltu( T a[], int n ) {
for (int i = 0; i < n; ++i) cerr << a[i] << ' ';
cerr << endl;
}
template <typename T, typename ... hello>
void faltu( T arg, const hello &... rest) { cerr << arg << ' '; faltu(rest...); }
// Program showing a policy-based data structure.
#include <ext/pb_ds/assoc_container.hpp> // Common file
#include <ext/pb_ds/tree_policy.hpp>
#include <functional> // for less
#include <iostream>
using namespace __gnu_pbds;
using namespace std;
// GNU link : https://goo.gl/WVDL6g
typedef tree<int, null_type, less_equal<int>, rb_tree_tag,
tree_order_statistics_node_update>
new_data_set;
/**___________________________________________________**/
const int N = 100005;
int idx, t;
int link[N];
int len[N];
int tr[N][26];
string s;
int occ[N];
void initTree()
{
memset(tr, 0, sizeof tr);
memset(link, 0, sizeof link);
memset(len, 0, sizeof len);
len[1] = -1;
link[1] = 1;
len[2] = 0;
link[2] = 1;
idx = 2;
t = 2;
}
void addletter(int pos)
{
while (s[pos - len[t] - 1] != s[pos]) t = link[t];
int x = link[t];
while (s[pos - len[x] - 1] != s[pos]) x = link[x];
int c = s[pos] - 'a';
if (!tr[t][c]) {
tr[t][c] = ++idx;
len[idx] = len[t] + 2;
link[idx] = len[idx] == 1 ? 2 : tr[x][c];
}
t = tr[t][c];
occ[t]++;
}
//https://vjudge.net/problem/HDU-3948
int main()
{
//FASTIO
/*
#ifndef ONLINE_JUDGE
freopen("in.txt", "r", stdin);
freopen("out.txt", "w", stdout);
freopen("error.txt", "w", stderr);
#endif
//*/
int T;
// scanf("%d", &T);
T = 1;
for (int cs = 1; cs <= T; cs++) {
initTree();
cin >> s;
s = ' ' + s;
int n = s.size();
for (int i = 1; i < n; i++) {
addletter(i);
}
// printf("Case #%d: %d\n", cs, idx - 2);
}
for (int i = idx; i > 2; i--)
occ[link[i]] += occ[i];
int ans = 0;
for (int i = 1; i <= idx; i++) {
ans = max(ans, len[i] * occ[i]);
}
cout << ans << "\n";
return 0;
}
