#include <bits/stdc++.h>
#include <iostream>
#include <string>
using namespace std;
typedef vector<int> vi;
typedef vector<vector<int>> vii;
#define rep(i, a, b) for(int i = a; i < b; i++)
struct node {
int n = 1, size = 0, suffix_link, next_link[26] = {};
};
class eertree {
public:
const int MAXN = 1000000;
int n;
vector<node> nodes;
int last = 3;
eertree(string s) {
n = s.size();
nodes.resize(MAXN);
nodes[1].size = -1; nodes[1].suffix_link = 1;
nodes[2].size = 0; nodes[2].suffix_link = 1;
int cur, cursize, suff = 1, let;
rep(pos, 0, n) {
cur = suff; let = s[pos]-'a';
while (true) {
cursize = nodes[cur].size;
// cout << "FIND "<< cur << " " << pos - cursize - 1 << " " << pos << endl;
if (pos - cursize - 1 >= 0 && s[pos - cursize - 1] == s[pos]) break;
cur = nodes[cur].suffix_link;
}
// cout << "pos: "<<pos<<endl;
if (nodes[cur].next_link[let]) {
// cout << "exists\n" << cur << " to " << let << endl;
cur = nodes[cur].next_link[let];
nodes[cur].n++;
suff = cur;
// while (cur > 2) {
// cout <<cur << " HEHEHE\n" ;
// nodes[cur].n++;
// cur = nodes[cur].suffix_link;
// }
}
else
{
nodes[cur].next_link[let] = last;
nodes[last].size = nodes[cur].size + 2;
while (true) {
// cout << cur << " " << pos - cursize - 1 << " " << pos << endl;
cursize = nodes[cur].size;
cur = nodes[cur].suffix_link;
if (pos - cursize - 1 >= 0 && s[pos - cursize - 1] == s[pos]) {
nodes[last].suffix_link = max(2, cur);
// while (cur > 2) {
// cout <<cur << " HEHEHE\n" ;
// nodes[cur].n++;
// cur = nodes[cur].suffix_link;
// }
break;
}
}
suff = last;
last++;
}
// cout << last << "!" << endl;
}
}
};
int main(){
string p;
cin >> p;
eertree e(p);
int best = 0;
for (auto &node : e.nodes) {
best = max(best, node.n * node.size);
}
cout << best << endl;
}
