#include <cstdio>
#define rep(i, d, u) for(int i = d; i <= u; ++i)
#define dep(i, u, d) for(int i = u; i >= d; --i)
int sred(char *st) {
	int re = 0;
	char ch;
	do {
		ch = getchar();
	} while('z' < ch || ch < 'a');
	do {
		st[++re] = ch;
	} while('a' <= (ch = getchar()) && ch <= 'z');
	return re;
}
void lwit(long long da) {
	int ch[21], cn = 0;
	do {
		ch[++cn] = da - da / 10 * 10;
	} while(da /= 10);
	do {
		putchar('0' ^ ch[cn]);
	} while(--cn);
}
void dmax(long long &le, long long ri) {
	if(le < ri) {
		le = ri;
	}
}
const int _maxn = 1000011, _maxb = 31;
int slen, sons[_maxn][_maxb], lasn, lens[_maxn], fail[_maxn], coun, dpot[_maxn];
char s[_maxn];
long long rans;
void adds(int at) {
	while(lasn && s[at] != s[at - lens[lasn] - 1]) {
		lasn = fail[lasn];
	}
	if(!sons[lasn][s[at] - 'a']) {
		lens[sons[lasn][s[at] - 'a'] = ++coun] = lens[lasn] + 2;
		int tn = fail[lasn];
		while(tn && s[tn] != s[tn - lens[lasn] - 1]) {
			tn = fail[tn];
		}
		if(tn) {
			fail[coun] = sons[tn][s[at] - 'a'];
		} else {
			fail[coun] = 2;
		}
	}
	lasn = sons[lasn][s[at] - 'a'];
}
int main() {
	slen = sred(s), lens[fail[coun = 2] = 1] = -1;
	rep(i, 1, slen) {
		adds(i), ++dpot[lasn];
	}
	dep(i, coun, 3) {
		dpot[fail[i]] += i;
	}
	rep(i, 3, coun) {
		dmax(rans, 1ll * dpot[i] * lens[i] * lens[i]);
	}
	lwit(rans), putchar('\n');
	return 0;
}