#include <bits/stdc++.h>
using namespace std;
#define int long long
//loops (warning : long long)
#define FOR(i, l, r) for(int i = (l); i < (r); ++i)
#define ROF(i, r, l) for(int i = (r - 1); i >= l; --i)
//pairs, tuples
#define mp make_pair
#define mt make_tuple
#define ff first
#define ss second
//vectors
#define all(v) begin(v), end(v)
#define rall(v) rbegin(v), rend(v)
#define pb push_back
#define eb emplace_back
#define sum_of(v) accumulate(all(v), 0ll)
#define sz(v) (int)v.size()
#define compact(v) v.erase(unique(all(v)), end(v))
//binary search
#define lwb lower_bound
#define upb upper_bound
//other stuffs
#define dbg(x) "[" #x " = " << (x) << "]"
#define file(task) if(fopen(task".inp", "r")){ freopen(task".inp", "r", stdin); freopen(task".out", "w", stdout); }
template<typename T>
bool minimize(T& a, const T& b){
if(a > b) return a = b, true;
return false;
}
template<typename T>
bool maximize(T& a, const T& b){
if(a < b) return a = b, true;
return false;
}
using ll = long long;
using ull = unsigned long long;
using ld = long double;
using db = double;
using pi = pair<int, int>;
using pl = pair<ll, ll>;
using vi = vector<int>;
using vb = vector<bool>;
using vl = vector<ll>;
using vpi = vector<pi>;
using vpl = vector<pl>;
mt19937_64 rng(chrono::steady_clock::now().time_since_epoch().count());
template<int _mod, int _alphabet>
struct HashString{ //[1, N]
const int mod = _mod;
const int alphabet = _alphabet;
int N;
vi base;
vector<array<int, 2>> h;
int add(int a, int b){
a += b; if(a >= mod) a -= mod;
return a;
}
int subtract(int a, int b){
a -= b; if(a < 0) a += mod;
return a;
}
int multiply(int a, int b){
return 1LL * a * b % mod;
}
HashString(vi& S, int N) : N(N), h(N + 2), base(N + 1) {
base[0] = 1;
FOR(i, 1, N + 1) assert(S[i] > 0);
FOR(i, 1, N + 1) base[i] = multiply(base[i - 1], alphabet);
FOR(i, 1, N + 1) h[i][0] = add(multiply(h[i - 1][0], alphabet), S[i]);
ROF(i, N + 1, 1) h[i][1] = add(multiply(h[i + 1][1], alphabet), S[i]);
}
int get_hash_forward(int l, int r){
return subtract(h[r][0], multiply(base[r - l + 1], h[l - 1][0]));
}
int get_hash_backward(int l, int r){
return subtract(h[l][1], multiply(base[r - l + 1], h[r + 1][1]));
}
};
struct PolynomialSegmentTree{
vl st, sum_pos, lazy_pos, lazy_add;
PolynomialSegmentTree(int n) : st(n << 2), sum_pos(n << 2), lazy_pos(n << 2), lazy_add(n << 2) {
build(1, 1, n);
}
void build(int id, int l, int r){
if(l == r){
sum_pos[id] += l;
} else{
int mid = l + r >> 1;
build(id << 1, l, mid);
build(id << 1 | 1, mid + 1, r);
sum_pos[id] = sum_pos[id << 1] + sum_pos[id << 1 | 1];
}
}
void apply_add(int id, int l, int r, ll v){
st[id] += v * (r - l + 1);
lazy_add[id] += v;
}
void apply_pos(int id, int l, int r, ll v){
st[id] += v * sum_pos[id];
lazy_pos[id] += v;
}
void lazy_down(int id, int l, int r, int mid){
if(lazy_add[id] != 0){
apply_add(id << 1, l, mid, lazy_add[id]);
apply_add(id << 1 | 1, mid + 1, r, lazy_add[id]);
lazy_add[id] = 0;
}
if(lazy_pos[id]){
apply_pos(id << 1, l, mid, lazy_pos[id]);
apply_pos(id << 1 | 1, mid + 1, r, lazy_pos[id]);
lazy_pos[id] = 0;
}
}
void update_add(int id, int l, int r, int u, int v, int x){
if(u <= l && r <= v){
apply_add(id, l, r, x);
} else{
int mid = l + r >> 1;
lazy_down(id, l, r, mid);
if(u <= mid) update_add(id << 1, l, mid, u, v, x);
if(mid < v) update_add(id << 1 | 1, mid + 1, r, u, v, x);
st[id] = st[id << 1] + st[id << 1 | 1];
}
}
void update_pos(int id, int l, int r, int u, int v, int x){
if(u <= l && r <= v){
apply_pos(id, l, r, x);
} else{
int mid = l + r >> 1;
lazy_down(id, l, r, mid);
if(u <= mid) update_pos(id << 1, l, mid, u, v, x);
if(mid < v) update_pos(id << 1 | 1, mid + 1, r, u, v, x);
st[id] = st[id << 1] + st[id << 1 | 1];
}
}
void polynomial_update(int l, int r, int n){
if(l <= r){
update_pos(1, 1, n, l, r, 1);
update_add(1, 1, n, l, r, -(l - 1));
}
}
void reversed_polynomial_update(int l, int r, int n){
if(l <= r){
update_pos(1, 1, n, l, r, -1);
update_add(1, 1, n, l, r, (r + 1));
}
}
vl trace(int n){
vl eval(n + 1);
auto rec = [&](auto self, int id, int l, int r) -> void{
if(l == r) eval[l] = st[id];
else{
int mid = l + r >> 1;
lazy_down(id, l, r, mid);
self(self, id << 1, l, mid);
self(self, id << 1 | 1, mid + 1, r);
}
};
rec(rec, 1, 1, n);
return eval;
}
};
void testcase(int ntestcase){
string S;
cin >> S;
int N = sz(S);
S = '?' + S;
vi s(N + 1);
FOR(i, 0, N) s[i + 1] = S[i + 1] - 'a' + 1;
HashString<(int)1e9 + 9, 31> mod1(s, N);
HashString<(int)1e9 + 7, 31> mod2(s, N);
function<bool(int, int, int, int)> match_palindrome = [&](int l1, int r1, int l2, int r2){ //1-index
return (min(l1, l2) > 0 && max(r1, r2) <= N) &&
(r1 - l1 == r2 - l2) &&
(mod1.get_hash_forward(l1, r1) == mod1.get_hash_backward(l2, r2)) &&
(mod2.get_hash_forward(l1, r1) == mod2.get_hash_backward(l2, r2));
};
vector<vl> addition(N + 1, vl(26)); //addition[i][c] = maximum delta if replace S[i] = 'a' + c
vi odd(N + 1), even(N + 1);
PolynomialSegmentTree T(N);
ll base = 0;
FOR(i, 1, N + 1){ //addition
if(i < N){
//even start from i and i + 1
int l = 1, r = min(i, N - i), eq = 0;
while(l <= r){
int mid = l + r >> 1;
if(match_palindrome(i - mid + 1, i, i + 1, i + mid)){
eq = mid; l = mid + 1;
} else r = mid - 1;
}
base += eq;
even[i] = eq;
if(even[i] > 0){
T.polynomial_update(i - even[i] + 1, i, N);
T.reversed_polynomial_update(i + 1, i + even[i], N);
}
if(i - eq > 0 && i + 1 + eq <= N){
//try to replace S[i - eq] = S[i + eq + 1]
//try to replace S[i + eq + 1] = S[i - eq]
int extra = 1;
l = 1, r = N;
while(l <= r){
int mid = l + r >> 1;
if(match_palindrome(i - eq - mid, i - eq - 1, i + eq + 2, i + eq + mid + 1)){
extra = 1 + mid;
l = mid + 1;
} else r = mid - 1;
}
int a = s[i - eq];
int b = s[i + eq + 1];
addition[i - eq][b] += extra;
addition[i + eq + 1][a] += extra;
}
}
int l = 2, r = min(i, N - i + 1), eq = 1;
while(l <= r){
int mid = l + r >> 1;
if(match_palindrome(i - mid + 1, i, i, i + mid - 1)){
eq = mid; l = mid + 1;
} else r = mid - 1;
}
base += eq;
odd[i] = eq;
if(odd[i] > 1){ //because change the center let unchanged
T.polynomial_update(i - odd[i] + 1, i - 1, N);
T.reversed_polynomial_update(i + 1, i + odd[i] - 1, N);
}
if(i - eq > 0 && i + eq <= N){
//try to replace S[i - eq] = S[i + eq]
//try to replace S[i + eq] = S[i - eq]
int extra = 1;
l = 1, r = N;
while(l <= r){
int mid = l + r >> 1;
if(match_palindrome(i - eq - mid, i - eq - 1, i + eq + 1, i + eq + mid)){
extra = 1 + mid; l = mid + 1;
} else r = mid - 1;
}
int a = s[i - eq];
int b = s[i + eq];
addition[i - eq][b] += extra;
addition[i + eq][a] += extra;
}
}
vl loss = T.trace(N);
ll max_delta = 0;
FOR(i, 1, N + 1){
FOR(c, 0, 26) if(c != s[i]){
ll cur = addition[i][c] - loss[i];
maximize(max_delta, cur);
}
}
cout << max_delta + base << '\n';
}
signed main(){
ios_base::sync_with_stdio(0); cin.tie(0);
#ifdef LOCAL
freopen("task.inp", "r", stdin);
#endif // LOCAL
int T = 1;
// cin >> T;
FOR(i, 0, T) testcase(i);
return 0;
}
