//Copyright © 2022 Youngmin Park. All rights reserved.
//#pragma GCC optimize("O3")
//#pragma GCC target("avx2")
#include <bits/stdc++.h>
using namespace std;
#define int long long
using ll = long long;
using vi = vector<int>;
using pii = pair<int, int>;
using vpi = vector<pii>;
using pll = pair<ll, ll>;
using vl = vector<ll>;
using vpl = vector<pll>;
using ld = long double;
template <typename T, size_t SZ>
using ar = array<T, SZ>;
#define all(v) (v).begin(), (v).end()
#define pb push_back
#define sz(x) (int)(x).size()
#define fi first
#define se second
#define lb lower_bound
#define ub upper_bound
#define FOR(i, a, b) for (int i = (a); i < (b); ++i)
#define F0R(i, a) FOR(i, 0, a)
#define ROF(i, a, b) for (int i = (b)-1; i >= (a); --i)
#define R0F(i, a) ROF(i, 0, a)
#define REP(a) F0R(_, a)
const int INF = 1e9;
const ll LINF = 1e18;
const int MOD = 1e9 + 7; //998244353;
const ld PI = acos((ld)-1.0);
const int dx[4] = {1, 0, -1, 0}, dy[4] = {0, 1, 0, -1};
mt19937_64 rng(chrono::steady_clock::now().time_since_epoch().count());
template <typename T>
using pqg = priority_queue<T, vector<T>, greater<T>>;
template <typename T>
bool ckmin(T &a, const T &b) { return b < a ? a = b, 1 : 0; }
template <typename T>
bool ckmax(T &a, const T &b) { return b > a ? a = b, 1 : 0; }
template <typename A, typename B>
ostream &operator<<(ostream &os, const pair<A, B> &p)
{
return os << '(' << p.first << ", " << p.second << ')';
}
template <typename T_container, typename T = typename enable_if<!is_same<T_container, string>::value, typename T_container::value_type>::type>
ostream &operator<<(ostream &os, const T_container &v)
{
os << '{';
string sep;
for (const T &x : v)
os << sep << x, sep = ", ";
return os << '}';
}
void dbg_out()
{
cerr << endl;
}
template <typename Head, typename... Tail>
void dbg_out(Head H, Tail... T)
{
cerr << ' ' << H;
dbg_out(T...);
}
#ifdef LOCAL
#define dbg(...) cerr << "(" << #__VA_ARGS__ << "):", dbg_out(__VA_ARGS__)
#else
#define dbg(...) 42
#endif
inline namespace RecursiveLambda{
template <typename Fun>
struct y_combinator_result{
Fun fun_;
template <typename T>
explicit y_combinator_result(T &&fun): fun_(forward<T>(fun)){}
template <typename...Args>
decltype(auto) operator()(Args &&...args){
return fun_(ref(*this), forward<Args>(args)...);
}
};
template <typename Fun>
decltype(auto) y_combinator(Fun &&fun){
return y_combinator_result<decay_t<Fun>>(forward<Fun>(fun));
}
};
void setIO(string s) // USACO
{
#ifndef LOCAL
freopen((s + ".in").c_str(), "r", stdin);
freopen((s + ".out").c_str(), "w", stdout);
#endif
}
constexpr int B = 9973;
int add(int a, int b) {
a += b;
if (a >= MOD) a -= MOD;
return a;
}
int mul(int a, int b) {
return 1LL * a * b % MOD;
}
int sub(int a, int b) {
a -= b;
if (a < 0) a += MOD;
return a;
}
int binPow(int a, int b) {
ll res = 1;
while (b) {
if (b & 1) res = (res * a) % MOD;
a = (1LL * a * a) % MOD;
b >>= 1LL;
}
return res;
}
struct HashRange {
vi t, power, inv;
HashRange(string &s) {
int n = sz(s);
t.resize(n + 1);
power.resize(n + 1);
inv.resize(n + 1);
power[0] = inv[0] = 1;
inv[1] = binPow(B, MOD - 2);
FOR(i, 1, n + 1) inv[i] = mul(inv[i - 1], inv[1]);
FOR(i, 1, n + 1) power[i] = mul(power[i - 1], B);
F0R(i, n) {
t[i + 1] = add(t[i], mul(power[i], s[i]));
}
}
int calcHash(int l, int r) { // 0 - indexed
return mul(sub(t[r + 1], t[l]), inv[l]);
}
};
void solve()
{
string s, t;
cin >> s;
int n = sz(s);
F0R(i, n) {
t += '#';
t += s[i];
}
t += '#';
HashRange hshF(t);
reverse(all(t));
HashRange hshB(t);
int nn = sz(t);
vi rd(nn);
vector<vi> a(nn, vi(26));
ll tot{}, ans{0};
reverse(all(t));
F0R(i, nn) {
int l = 0, r = min(i, nn - 1 - i), ret = 0;
while (l <= r) {
int mid = (l + r) >> 1;
if (hshF.calcHash(i, i + mid) == hshB.calcHash(nn - 1 - i, nn - 1 - i + mid)) {
ret = mid; l = mid + 1;
}else r = mid - 1;
}
rd[i] = ret;
if (i & 1) {
tot += (ret + 1) / 2;
}else tot += ret / 2;
if (i - ret > 0 && i + ret + 1 < nn) {
char c = t[i + ret + 1];
char d = t[i - ret - 1];
dbg(i, c, d);
l = 1, r = min(i - ret - 1, nn - 1 - i - ret - 1);
int z = 0;
while (l <= r) {
int mid = (l + r) >> 1;
if (hshF.calcHash(i + ret + 2, i + ret + 1 + mid) == hshB.calcHash(nn - 1 - (i - ret - 2), nn - 1 - (i - ret - 1) + mid)) {
z = mid, l = mid + 1;
}else r = mid - 1;
}
a[i - ret - 1][c - 'a'] += z / 2 + 1;
a[i + ret + 1][d - 'a'] += z / 2 + 1;
dbg(z);
}
}
int sum{}, cnt{};
vpi fr(nn);
vpi bk(nn);
F0R(i, nn) {
char c = t[i];
if (c != '#') {
int z = (sum - (i + 1) * cnt) / 2 + cnt;
F0R(j, 26) {
if (j == c - 'a') continue;
a[i][j] -= z;
}
}
sum += i + rd[i];
cnt++;
fr[i + rd[i]].fi += i + rd[i];
fr[i + rd[i]].se++;
sum -= fr[i].fi;
cnt -= fr[i].se;
}
cnt = sum = 0;
R0F(i, nn) {
char c = t[i];
if (c != '#') {
int z = ((i - 1) * cnt - sum) / 2 + cnt;
dbg(z);
F0R(j, 26) {
if (j == c - 'a') continue;
a[i][j] -= z;
}
}
sum += i - rd[i];
cnt++;
bk[i - rd[i]].fi += i - rd[i];
bk[i - rd[i]].se++;
sum -= bk[i].fi;
cnt -= bk[i].se;
}
F0R(i, nn) {
if (i & 1) {
F0R(j, 26) {
ckmax(ans, tot + a[i][j]);
}
}
}
cout << ans << '\n';
}
int32_t main()
{
cin.tie(0)->sync_with_stdio(0);
cin.exceptions(cin.failbit);
int testcase=1;
// cin >> testcase;
while (testcase--)
{
solve();
}
}
