//qoj275
#include <bits/stdc++.h>
using namespace std; typedef long long ll;
void solve();int main(){ solve(); return 0; }

const int N = 3e5 + 10;
int n, tot = 1, len[N], sum[N], ch[N][26], fl[N], cur;
char s[N];

int gfl(int x, int i){
	while(i - len[x] - 1 < 0 || s[i-len[x]-1] != s[i]){
		x = fl[x];
	}
	return x;
}

void solve(){
	scanf("%s", s + 1);
	n = strlen(s + 1);
	fl[0] = 1;
	len[1] = -1;
	for(int i = 1; i <= n; ++ i){
		int pos = gfl(cur, i);
		if(!ch[pos][s[i]-'a']){
			fl[++tot] = ch[gfl(fl[pos], i)][s[i]-'a'];
			ch[pos][s[i]-'a'] = tot;
			len[tot] = len[pos] + 2;
		}
		cur = ch[pos][s[i]-'a'];
		++ sum[cur];
	}
	for(int i = tot; i >= 0; -- i){
		sum[fl[i]] += sum[i];
	}
	ll ans = 0;
	for(int i = 0; i <= tot; ++ i){
		ans = max(ans, (ll)len[i] * sum[i]);
	}
	printf("%lld\n", ans);
	return;
}