#include <bits/stdc++.h>
#pragma GCC optimize ("O3")
#pragma GCC target ("sse4")
using namespace std;
#define int long long int
const int N = 1e5 + 10;
const int md = 1e9 + 7;
const int INF = 1e18;
int32_t main(int32_t argc, char *argv[]) {
ios::sync_with_stdio(false);
cin.tie(nullptr);
int T = 1;
// cin >> T;
while (T--) {
string s;
cin >> s;
int n = (int) s.size();
s = '#' + s;
vector<vector<bool>> dp(n + 1, vector<bool> (n + 1));
map<string, int> mp;
int ans = 0;
for (int i = 1; i <= n; i++) {
dp[i][i] = 1;
string c = "";
c += s[i];
mp[c]++;
ans = max(ans, mp[c]);
for (int j = i - 1; j >= 1; j--) {
c = s[j] + c;
if (j == i - 1) {
if (s[j] == s[i]) {
int cnt = (++mp[c]);
dp[j][i] = 1;
ans = max(ans, cnt * 2);
}
}
else if (s[i] == s[j] && dp[j + 1][i - 1]) {
int cnt = (++mp[c]);
dp[j][i] = 1;
ans = max(ans, (i - j + 1) * cnt);
}
}
}
cout << ans << '\n';
}
return 0;
}
