#include "bits/stdc++.h"
using namespace std;
const int maxn = 600005;
using ll = long long;
int t[maxn][26], link[maxn], len[maxn];
int node, cur;
ll dp[maxn];
string s;
void init(){
len[1] = -1;
len[2] = 0;
link[1] = 1;
link[2] = 1;
node = cur = 2;
}
void extend(int idx){
while(s[idx - len[cur] - 1] != s[idx]){
cur = link[cur];
}
int x = link[cur];
while(s[idx - len[x] - 1] != s[idx]){
x = link[x];
}
int c = s[idx] - 'a';
if(!t[cur][c]){
t[cur][c] = ++node;
len[node] = len[cur] + 2;
if(len[node] == 1){
link[node] = 2;
}else {
link[node] = t[x][c];
}
}
cur = t[cur][c];
dp[cur]++;
}
int main(int argc, char const *argv[])
{
ios::sync_with_stdio(false);
cin.tie(0);
cin >> s;
s = "#" + s;
init();
int n = s.size();
for(int i = 1; i < n; ++i){
extend(i);
}
ll ans = 0;
for(int i = node; i > 2; --i){
dp[link[i]] += dp[i];
}
for(int i = node; i > 2; --i){
ans = max(ans, len[i] * 1LL * dp[i]);
}
cout << ans << endl;
return 0;
}
