#include <bits/stdc++.h>
using namespace std;
#define N 350000
struct Node {
int cnt, len, sufflink, next[26];
}tree[N];
vector<int> e[N];
struct PalindromicTree {
string s;
int currNode, ptr;
long long ans;
PalindromicTree(string s): s(s) {
currNode = ptr = 1;
for(int i = 0; i<N; i++) {
tree[i].len = tree[i].cnt = tree[i].sufflink = 0;
for (int j = 0; j<26; j++) tree[i].next[j] = 0;
}
tree[0].len = -1; tree[0].sufflink = 0;
for (int i = 0; i<(int) s.size(); i++) insert(i);
}
long long getMaxAns() {
ans = 0;
dfs(1);
return ans;
}
private:
void insert(int pos) {
int cur = currNode;
int let = s[pos] - 'a';
while (true) {
int curLen = tree[cur].len;
if (pos - curLen >= 1 && s[pos] == s[pos - curLen - 1]) break;
cur = tree[cur].sufflink;
}
if (tree[cur].next[let]) {
currNode = tree[cur].next[let];
tree[currNode].cnt++;
return;
}
currNode = ++ptr;
tree[cur].next[let] = ptr;
tree[ptr].cnt = 1;
tree[ptr].len = tree[cur].len + 2;
if (tree[ptr].len == 1) {
tree[ptr].sufflink = 1;
e[1].push_back(ptr);
return;
}
cur = tree[cur].sufflink;
while (true) {
int curLen = tree[cur].len;
if (pos - curLen >= 1 && s[pos] == s[pos - curLen - 1]) {
tree[currNode].sufflink = tree[cur].next[let];
e[tree[currNode].sufflink].push_back(ptr);
return;
}
cur = tree[cur].sufflink;
}
}
void dfs(int u) {
for (int v : e[u]) {
dfs(v);
tree[u].cnt += tree[v].cnt;
}
ans = max(ans, 1ll * tree[u].len * 1ll * tree[u].cnt);
}
};
string s;
int main() {
//freopen("palindrome.inp","r",stdin);
//freopen("palindrome.out","w",stdout);
ios::sync_with_stdio(false);cin.tie(NULL);
cin.tie(NULL);cout.tie(NULL);
cin>>s;
PalindromicTree PT(s);
cout<<PT.getMaxAns();
}
