#include <bits/stdc++.h>
using namespace std;
typedef long long ll;

#define eb emplace_back
#define rep(i, a, b) for (int i = (a); i <= (b); ++i)
#define per(i, a, b) for (int i = (a); i >= (b); --i)

const int N = 400001;

//const int mod = 998244353;

ll ans = 0;

struct Palindromic_AutoMaton {
    vector<int> str;
    int nxt[N][26], fail[N], len[N];   
    int num[N], last, tot;
    void clear() {
        len[1] = -1; fail[1] = 0;
        len[0] = 0; fail[0] = 1;
        str.clear(); str.eb(-1);
        last = 0; tot = 1;
        memset(nxt[0], 0, sizeof(nxt[0]));
        memset(nxt[1], 0, sizeof(nxt[1]));
    }
    Palindromic_AutoMaton(){clear();}
    int newnode(int _len) {
        len[++tot] = _len;
        fail[tot] = num[tot] = 0; 
        memset(nxt[tot], 0, sizeof(nxt[tot]));
        return tot;
    }
    int get_fail(int u) {
        int strlen = str.size() - 1;
        while (str[strlen - len[u] - 1] != str[strlen]) u = fail[u];
        return u;
    }
    void append(int ch) {
        str.emplace_back(ch);
        int fat = get_fail(last);
        if (!nxt[fat][ch]) {
            int cur = newnode(len[fat] + 2);
            fail[cur] = nxt[get_fail(fail[fat])][ch];
            nxt[fat][ch] = cur; 
        }
        last = nxt[fat][ch];
        ++num[last];
    }
    void add(string &s) {
        for (auto &ch : s) append(ch - 'a');
    }
    void get_cnt() {
        per(u, tot, 2) num[fail[u]] += num[u];
        num[0] = num[1] = 0;
    }
    void calc() {
        rep(u, 2, tot) ans = max(ans, 1ll * len[u] * num[u]);
    }
} pam;

int main() {
    cin.tie(0);
    ios::sync_with_stdio();
    string s; cin >> s;
    pam.add(s);
    pam.get_cnt();
    pam.calc();
    cout << ans;
    return 0;
}