#include <bits/stdc++.h>
using namespace std;
#define ll long long int
#define sz(x) (int)x.size()
#define ff first
#define ss second
const ll N = 5005;
const ll M = 1e9 + 7;
int a[N][N], b[N];
int f(char c){
return (c-'a');
}
int main(){
ios::sync_with_stdio(false); cin.tie(0);
string s;
cin >> s;
int n = sz(s), ans = 0;
for(int i = 0; i < n; i++){
int l = i, r = i, l1 = -1, r1 = n;
bool tr = 0;
while(l >= 0 and r < n){
if(s[l] == s[r]){
if(tr == 0){
ans++;
}
else {
a[l1][f(s[r1])]++;
a[r1][f(s[l1])]++;
}
}
else {
if(tr == 1) break;
tr = 1;
l1 = l, r1 = r;
a[l][f(s[r])]++;
a[r][f(s[l])]++;
}
l--;
r++;
if(tr == 0){
l1 = l, r1 = r;
}
}
int l2 = l1+1, r2 = r1-1;
while(l2 < i){
b[l2] += abs(l2-l1);
b[r2] += abs(r1-r2);
l2++;
r2--;
}
}
for(int i = 0; i < n-1; i++){
int l = i, r = i+1, l1 = -1, r1 = n;
bool tr = 0;
while(l >= 0 and r < n){
if(s[l] == s[r]){
if(tr == 0){
ans++;
}
else {
a[l1][f(s[r1])]++;
a[r1][f(s[l1])]++;
}
}
else {
if(tr == 1) break;
tr = 1;
l1 = l, r1 = r;
a[l][f(s[r])]++;
a[r][f(s[l])]++;
}
l--;
r++;
if(tr == 0){
l1 = l, r1 = r;
}
}
int l2 = l1+1, r2 = r1-1;
while(l2 <= i){
b[l2] += abs(l2-l1);
b[r2] += abs(r1-r2);
l2++;
r2--;
}
}
int mx = 0;
for(int i = 0; i < n; i++){
for(int j = 0; j < 26; j++){
mx = max(mx,a[i][j]-b[i]);
}
}
cout << ans + mx;
return 0;
}
