#include <bits/stdc++.h>
using namespace std;
using ll = long long;
struct PAM {
// 0 -> even root, 1 -> odd root
static constexpr int ALPHABET_SIZE = 26;
struct Node {
int len, fail;
array<int, ALPHABET_SIZE> next;
Node() : len{}, fail{}, next{} {}
};
vector<int> s;
vector<Node> t;
PAM() { init(); }
void init() {
s.clear();
t.assign(2, Node());
t[0].len = 0, t[1].len = -1;
t[0].fail = t[1].fail = 1;
}
int newNode() {
t.emplace_back();
return t.size() - 1;
}
int extend(int p, int c) {
int i = s.size();
s.push_back(c);
while (s[i - t[p].len - 1] != c)
p = t[p].fail;
if (!t[p].next[c]) {
int r = newNode(), v = t[p].fail;
t[r].len = t[p].len + 2;
while (s[i - t[v].len - 1] != c)
v = t[v].fail;
t[r].fail = t[v].next[c];
t[p].next[c] = r;
}
return p = t[p].next[c];
}
};
int main() {
ios::sync_with_stdio(false);
cin.tie(nullptr);
string s;
cin >> s;
int n = s.length();
vector<int> last(n + 1);
last[0] = 1;
PAM pam;
for (int i = 0; i < n; i++) {
last[i + 1] = pam.extend(last[i], s[i] - 'a');
}
int sz = pam.t.size();
vector<int> cnt(sz);
for (int i = 1; i <= n; i++) {
cnt[last[i]]++; // 去重 = 1
}
ll ans = 0;
for (int i = sz - 1; i >= 0; i--) {
cnt[pam.t[i].fail] += cnt[i];
ans = max(ans, 1LL * pam.t[i].len * cnt[i]);
}
cout << ans << "\n";
// string s;
// cin >> s;
// int n = s.length();
// PAM pam;
// vector<int> last(n + 1);
// last[0] = 1;
// vector<int> a(n);
// for (int i = 0; i < n; i++) {
// a[i] = s[i];
// }
// vector<int> ans(n + 1);
// for (int i = 0; i < n; i++) {
// a[i] = (a[i] - 97 + ans[i]) % 26 + 97;
// last[i + 1] = pam.extend(last[i], a[i] - 'a');
// ans[i + 1] = cnt.back();
// }
// for (int i = 0; i < n; i++) {
// cout << ans[i + 1] << " \n"[i == n - 1];
// }
return 0;
}
