#include <bits/stdc++.h>
#define N 341467
#define count scx
using namespace std;

typedef long long ll;

char s[N], *ptr;
int d[N][26], fail[N], val[N], count[N];
int i, cnt = 1, p, last = 0; ll ans = 0;

inline void up(ll &x, const ll y) {x < y ? x = y : 0;}
int get_fail(int x) {for(; *(ptr - (val[x] + 1)) != *ptr; x = fail[x]); return x;}

void extend(int x){
    p = get_fail(last);
    int &q = d[p][x];
    if(!q) {fail[++cnt] = d[get_fail(fail[p])][x]; val[q = cnt] = val[p] + 2;}
    ++count[last = q];
}

int main(){
    s[0] = val[1] = -1; fail[0] = 1; scanf("%s", s + 1);
    for(ptr = s; *ptr; ++ptr) extend(*ptr - 'a');
    for(i = cnt; i > 1; --i) count[fail[i]] += count[i];
    for(i = 2; i <= cnt; ++i) up(ans, (ll)count[i] * val[i]);
    printf("%lld\n", ans);
    return 0;
}