#include <bits/stdc++.h>
using namespace std;
#define X first
#define Y second
#define mp make_pair
#define pb push_back
typedef long long ll;
typedef pair <int, int> pii;
typedef pair <int, pii> pip;
typedef pair <pii, int> ppi;
typedef pair <ll, ll> pll;
const int INF=0x3f3f3f3f;
const int N=3e5+5;
const int LOG=20;
int n;
char s[N];
int suff[N], lcp[N];
int odd[N], even[N];
int rmq[LOG][N];
int ind[N], novi[N];
vector <int> vec[N];
#define DEBUG 0
int counter[30];
int cmp(int a, int b) {
return s[a]<s[b];
}
inline int modaj(int x) {
return x>=n ? x-n : x;
}
void build_suff() {
s[n]='$'; s[n+1]='\0'; n++;
for (int i=0; i<n; ++i) suff[i]=i;
sort(suff, suff+n, cmp);
ind[suff[0]]=0;
for (int i=1; i<n; ++i) ind[suff[i]]=ind[suff[i-1]]+(s[suff[i]]!=s[suff[i-1]]);
for (int j=1; j<n; j*=2) {
for (int i=0; i<n; ++i) vec[i].clear();
for (int i=0; i<n; ++i) {
suff[i]=modaj(suff[i]-j+n);
vec[ind[suff[i]]].pb(suff[i]);
}
int curr=0;
for (int i=0; i<n; ++i)
for (int x:vec[i])
suff[curr++]=x;
novi[suff[0]]=0;
for (int i=1; i<n; ++i) {
if (ind[suff[i-1]]==ind[suff[i]] && ind[modaj(suff[i-1]+j)]==ind[modaj(suff[i]+j)]) novi[suff[i]]=novi[suff[i-1]];
else novi[suff[i]]=novi[suff[i-1]]+1;
}
memcpy(ind, novi, sizeof(novi));
}
}
void build_lcp() {
int lc=0;
for (int i=0; i<n-1; ++i) {
int curr=ind[i];
int j=suff[curr-1];
while (s[i+lc]==s[j+lc]) lc++;
lcp[curr-1]=lc;
lc=max(lc-1, 0);
}
}
void build_rmq() {
for (int i=0; i<n; ++i) rmq[0][i]=lcp[i];
for (int i=1; i<LOG; ++i) {
for (int j=0; j<n; ++j) {
rmq[i][j]=rmq[i-1][j];
if (j+(1<<i)<=n) rmq[i][j]=min(rmq[i][j], rmq[i-1][j+(1<<(i-1))]);
}
}
}
int broj(int pos, int d) {
int l=ind[pos]-1, r=ind[pos];
int res=0;
for (int i=LOG-1; i>=0; --i) {
if (r+(1<<i)<=n && rmq[i][r]>=d) r+=(1<<i);
if (l-(1<<i)>=-1 && rmq[i][l-(1<<i)+1]>=d) l-=(1<<i);
}
return r-l;
}
void solve() {
build_suff();
build_lcp();
build_rmq();
#if DEBUG
for (int i=0; i<n; ++i) printf("%d ", suff[i]);
printf("\n");
for (int i=0; i<n; ++i) printf("%d ", lcp[i]);
printf("\n");
#endif // DEBUG
ll sol=0;
for (int i=0; i<n-1; ++i) counter[s[i]-'a']++;
for (int i=0; i<26; ++i) sol=max(sol, (ll)counter[i]);
odd[0]=1;
int cent=0, r=0;
for (int i=1; i<n-1; ++i) {
odd[i]=(i>r) ? 1 : min(r-i+1, odd[cent-(i-cent)]);
while (i-odd[i]>=0 && i+odd[i]<n && s[i-odd[i]]==s[i+odd[i]]) {
sol=max(sol, (ll)broj(i-odd[i], odd[i]*2+1)*(odd[i]*2+1));
odd[i]++;
}
if (i+odd[i]-1>r) cent=i, r=i+odd[i]-1;
}
even[0]=0;
cent=0, r=0;
for (int i=1; i<n-1; ++i) {
even[i]=(i>r) ? 0 : min(r-i+1, even[cent-(i-cent)-1]);
while (i-even[i]-1>=0 && i+even[i]<n && s[i-even[i]-1]==s[i+even[i]]) {
sol=max(sol, (ll)broj(i-even[i]-1, even[i]*2+2)*(even[i]*2+2));
even[i]++;
}
if (i+even[i]-1>r) cent=i, r=i+even[i]-1;
}
printf("%lld\n", sol);
}
void load() {
scanf("%s", s);
n=strlen(s);
}
int main() {
load();
solve();
return 0;
}
