#pragma GCC optimize("O3,unroll-loops")
// #pragma GCC target("avx,popcnt,sse4,abm")
#include<bits/stdc++.h>
using namespace std;
#define ZTMYACANESOCUTE ios_base::sync_with_stdio(0), cin.tie(0)
#define ll long long
#define ull unsigned long long
#define pb push_back
#define all(a) (a).begin(), (a).end()
#define debug(x) cerr << #x << " = " << x << '\n';
#define rep(X, a, b) for(int X = a; X < b; ++X)
#define pii pair<int, int>
#define pll pair<ll, ll>
#define pld pair<ld, ld>
#define ld long double
#define F first
#define S second
pii operator + (const pii &p1, const pii &p2) { return make_pair(p1.F + p2.F, p1.S + p2.S); }
pii operator - (const pii &p1, const pii &p2) { return make_pair(p1.F - p2.F, p1.S - p2.S); }
pll operator + (const pll &p1, const pll &p2) { return make_pair(p1.F + p2.F, p1.S + p2.S); }
pll operator - (const pll &p1, const pll &p2) { return make_pair(p1.F - p2.F, p1.S - p2.S); }
template<class T> bool chmin(T &a, T b) { return (b < a && (a = b, true)); }
template<class T> bool chmax(T &a, T b) { return (a < b && (a = b, true)); }
#define lpos pos << 1
#define rpos pos << 1 | 1
template<typename A, typename B> ostream& operator<<(ostream &os, const pair<A, B> &p) { return os << '(' << p.first << "," << p.second << ')'; }
template<typename A> ostream& operator << (ostream &os, const vector<A> &p) { for(const auto &a : p) os << a << " "; os << '\n'; return os; }
const int MAXN = 3e5 + 5, MOD = 998244353, IINF = 1e9 + 7, MOD2 = 1000000007;
const double eps = 1e-9;
const ll LINF = 1e18L + 5;
const int B = 320;
// mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());
// int get_rand(int l, int r){ return uniform_int_distribution<int>(l, r)(rng); }
ll fpow(ll x, ll exp, ll mod = LLONG_MAX){ ll res = 1; while(exp){ if(exp & 1) res = res * x % mod; x = x * x % mod; exp >>= 1;} return res; }
int to[MAXN][26], fail[MAXN], cnt[MAXN], len[MAXN], sz;
string s;
int extend() {
fill(to[sz], to[sz] + 26, 0), sz++;
return sz - 1;
}
void init() {
sz = 0, extend(), extend();
len[0] = 0, fail[0] = 1, len[1] = -1;
int last = 1;
rep (i, 0, s.size()) {
while (s[i - len[last] - 1] != s[i]) last = fail[last];
if (!to[last][s[i] - 'a']) {
int idx = extend();
len[idx] = len[last] + 2;
int now = fail[last];
while (s[i - len[now] - 1] != s[i]) now = fail[now];
fail[idx] = to[now][s[i] - 'a'];
to[last][s[i] - 'a'] = idx;
}
last = to[last][s[i] - 'a'];
cnt[last]++;
}
}
void build_count() {
for (int i = sz - 1; i > 1; --i) cnt[fail[i]] += cnt[i];
}
void solve() {
cin >> s;
init();
build_count();
ll ans = 0;
rep (i, 0, sz) chmax(ans, 1LL * len[i] * cnt[i]);
cout << ans << '\n';
}
int main() {
ZTMYACANESOCUTE;
int T = 1;
// cin >> T;
while (T--) {
solve();
}
}
