#include <bits/stdc++.h>
using namespace std;
using ll = long long;
#define ii pair<int, int>
#define f first
#define s second
#define pb push_back
#define mp make_pair
#define all(x) x.begin(), x.end()
#define F0R(i, n) for (int i = 0; i < n; i++)
#define FOR(i, a, b) for (int i = a; i < b; i++)
#define inf 1000000010
const ll M = 1e9+9, P = 9973;
int n;
string s[2];
ll hsh[2][210001];
ll pw[210001];
ll extra[210001][26];
ll numPalindromes[210001];
int deltaDelta[210001];
ll getHash(int a, int b, int c) {
assert(a >= 0 && a < n && b >= 0 && b < n);
if (c == 1) {
int tmp = a;
a = n-1 - b;
b = n-1 - tmp;
}
return (hsh[c][b+1]-(hsh[c][a]*pw[b-a+1])%M+M)%M;
}
int main() {
cin.tie(0)->sync_with_stdio(0);
string tmp; cin >> tmp;
s[0].resize((int)tmp.size()*2+1);
for (int i = 0; i < (int)tmp.size(); i++) {
s[0][i*2] = '#';
s[0][i*2+1] = tmp[i];
}
s[0][(int)tmp.size()*2] = '#';
n = s[0].length();
s[1] = s[0];
reverse(all(s[1]));
hsh[0][0] = 1;
hsh[1][0] = 1;
pw[0] = 1;
F0R(i, n) {
hsh[0][i+1] = ((hsh[0][i]*P)%M+s[0][i])%M;
hsh[1][i+1] = ((hsh[1][i]*P)%M+s[1][i])%M;
pw[i+1] = pw[i]*P%M;
}
ll base = 0;
F0R(i, n) {
// calculate radius of palindrome
int lo = 0, hi = min(i, n-i-1)+1, r = 0;
while (lo < hi) {
int mid = (lo+hi)/2;
bool valid = getHash(i-mid, i, 0) == getHash(i, i+mid, 1);
if (valid) {
r = mid;
lo = mid + 1;
} else {
hi = mid;
}
}
if (r != 0) {
deltaDelta[i-r]++;
deltaDelta[i+1]-=2;
deltaDelta[i+r+2]++;
}
base += (r+1)/2;
F0R(j, 26) extra[i][j] += (r+1)/2;
int x = i-r-1, y = i+r+1;
if (x < 0 || x >= n || y < 0 || y >= n) continue;
// fix the boundary, calculate the new radius of palindrome
lo = 0, hi = min(i-r-1, n-(i+r+1)-1)+1; int r2 = 0;
while (lo < hi) {
int mid = (lo+hi)/2;
bool valid = getHash(i-r-1-mid, i-r-2, 0) == getHash(i+r+2, i+r+1+mid, 1);
if (valid) {
r2 = mid;
lo = mid + 1;
} else {
hi = mid;
}
}
r2++;
assert(s[0][x] != '#' && s[1][y] != '#');
extra[x][s[0][y]-'a'] += r2/2;
extra[y][s[0][x]-'a'] += r2/2;
}
ll delta = 0, tot = 0;
F0R(i, n) {
delta += deltaDelta[i];
tot += delta;
numPalindromes[i] = tot/2;
}
ll best = 0;
F0R(i, n) {
if (i%2 == 1) {
F0R(j, 26) {
best = max(best, extra[i][j] - numPalindromes[i]);
}
}
}
cout << base+best << endl;
return 0;
}
