#include <bits/stdc++.h>
using namespace std;
using ll = long long;
using ld = long double;
using ull = unsigned long long;
constexpr bool typetest = 0;
constexpr int N = 3e5 + 2;
constexpr ll Inf = 1e17;
struct node
{
node *child[26], *sufflink;
vector<node *> adj;
int len, cnt;
node()
{
len = 0;
cnt = 0;
for (int i = 0; i < 26; ++i)
child[i] = NULL;
sufflink = NULL;
}
};
struct PalindromeTree
{
node even, odd;
PalindromeTree()
{
odd.len = -1;
odd.sufflink = &odd;
even.sufflink = &odd;
odd.adj.emplace_back(&even);
even.len = 0;
}
void Assign(string &s)
{
node *last = &even;
for (int i = 1; i < (int)s.size(); ++i)
{
node *tmp = last;
while (s[i - tmp->len - 1] != s[i])
tmp = tmp->sufflink;
if (tmp->child[s[i] - 'a'])
{
last = tmp->child[s[i] - 'a'];
++last->cnt;
continue;
}
last = tmp->child[s[i] - 'a'] = new node;
last->len = tmp->len + 2;
++last->cnt;
if (last->len == 1)
{
last->sufflink = &even;
even.adj.emplace_back(last);
continue;
}
do
{
tmp = tmp->sufflink;
} while (s[i - tmp->len - 1] != s[i]);
last->sufflink = tmp->child[s[i] - 'a'];
last->sufflink->adj.emplace_back(last);
}
}
ll dfs(node *v)
{
ll res(-Inf);
for (auto i : v->adj)
{
res = max(res, dfs(i));
v->cnt += i->cnt;
}
return max(res, 1ll * v->len * v->cnt);
}
} f;
string s;
void Read()
{
cin >> s;
s = " " + s;
}
void Solve()
{
f.Assign(s);
cout << f.dfs(&f.odd);
}
int32_t main()
{
ios::sync_with_stdio(0);
cin.tie(0);
cout.tie(0);
int t(1);
if (typetest)
cin >> t;
for (int _ = 1; _ <= t; ++_)
{
Read();
Solve();
}
}
