#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, size, suffix_link, next[40] = {0};
};
int MAXN = 1000000;
class EerTree {
public:
vector<node> nodes;
EerTree(string s) {
nodes.resize(MAXN);
nodes[1].size = -1; nodes[1].suffix_link = 1;
nodes[2].size = 0; nodes[2].suffix_link = 1;
int cur, suff = 2, n = s.size(), cursize, let, last = 3;
rep(pos, 0, n) {
cur = suff; let = s[pos] - 'a';
// cout << pos << " " << s[pos] << " "<< cur << " " << nodes[cur].suffix_link << endl;
while (true) {
cursize = nodes[cur].size;
// cout << cur << " " << nodes[cur].suffix_link <<" "<< cursize << endl;
if (pos - cursize - 1 >= 0 && s[pos - cursize - 1] == s[pos]) break;
cur = nodes[cur].suffix_link;
}
if (nodes[cur].next[let])
{
cur = nodes[cur].next[let];
nodes[cur].n++;
int add = cur;
suff = nodes[cur].suffix_link;
while (add > 2) {add = nodes[add].suffix_link; nodes[add].n++;}
}
else
{
nodes[last].n = 1;
nodes[last].size = nodes[cur].size + 2;
nodes[cur].next[let] = last;
while (true) {
// cout << cur << endl;
cur = nodes[cur].suffix_link;
cursize = nodes[cur].size;
if (cur == 1 && nodes[cur].next[let] == last) {
nodes[last].suffix_link = 2; break;
}
if (pos - cursize - 1 >= 0 && s[pos - cursize - 1] == s[pos]) {
nodes[last].suffix_link = nodes[cur].next[let];
break;
}
}
// cout << "new " << last << ", suffix link: " << nodes[last].suffix_link << endl;
int add = nodes[last].suffix_link;
while (add > 2) {nodes[add].n++; add = nodes[add].suffix_link;}
suff = last;
last++;
}
}
}
};
int main() {
string s;cin>>s;
EerTree et(s);
int best = 0;
for (auto &nd : et.nodes) best = max(best, nd.n * nd.size);
// for (auto &nd : et.nodes) cout << nd.n << " " << nd.size << " " << endl;
cout << best << endl;
}
