#include <bits/stdc++.h>
using namespace std;
using ll = long long; using pii = pair<ll,ll>;
const ll a = 1234567; const ll p = 1e9+7; //hash values
ll ans = 0;
const ll Nm = 6e5+5; ll N;
ll aexp[Nm+1];
ll phsh[Nm+1];
ll pihsh[Nm+1];
ll tval[Nm];
ll prad[Nm]; //permutation radius
ll ghsh(ll l, ll r) { //[l,r]
ll v = phsh[r+1]-aexp[r+1-l]*phsh[l];
v = (v+p*(-v/p+2))%p;
return v;
}
ll gihsh(ll l0, ll r0) { //[l,r]
ll l = Nm-1-r0; ll r = Nm-1-l0;
ll v = pihsh[r+1]-aexp[r+1-l]*pihsh[l];
v = (v+p*(-v/p+2))%p;
return v;
}
unordered_map<ll,ll> fdeg; //forward degree (hash -> children)
unordered_map<ll,ll> radj; //reverse adjacency (parent -> this)
unordered_map<ll,ll> hrad; //radius of hash
unordered_map<ll,ll> ival; //intrinsic value
inline void aug(unordered_map<ll,ll>& m0, ll v, ll del=1) {
if (m0.find(v)!=m0.end()) {
m0[v]+=del;
} else {
m0[v]=del;
}
}
//ll CLOCK = 0;
void process(vector<ll> velem, ll l, ll r) {
// cout << "process: l,r="<<l<<","<<r<<"\nvelem:\n";
// for (ll x: velem) {
// cout << x << " ";
// }
// cout << "\n";
// if (CLOCK++>=4) {
// exit(0);
// }
if (velem.size()==0) {
return;
}
ll M = velem.size();
vector<ll> v0,v1;
for (ll i=0;i<M;i++) {
ll x = velem[i];
if (prad[x]>=l) {
v0.push_back(ghsh(x,x+l));
hrad[v0[i]]=l;
aug(ival,v0[i],0);
aug(fdeg,v0[i],0);
} else {
assert(1==2);
v0.push_back(-1);
}
}
for (ll i=0;i<M;i++) {
ll x = velem[i];
if (prad[x]>=r) {
v1.push_back(ghsh(x,x+r));
hrad[v1[i]]=r;
aug(ival,v1[i],0);
aug(fdeg,v1[i],0);
} else {
v1.push_back(-1);
}
}
//v1 shouldn't have repeats other than -1s
//repeats possibly present in v0? also no -1s
if ((r-1)==l) { //process
for (ll i=0;i<M;i++) {
if (v1[i]==-1) {
aug(ival,v0[i]);
// cout << "aug ival for x,rad="<<velem[i]<<","<<l<<"\n";
radj[v0[i]]=-1;
} else {
radj[v1[i]]=v0[i];
aug(fdeg,v0[i]);
}
}
return;
}
if (M==1) {
if (v1[0]!=-1) {
radj[v1[0]]=v0[0];
aug(fdeg,v0[0]);
} else {
ll shsh = ghsh(velem[0],velem[0]+prad[velem[0]]);
if (shsh==v0[0]) {
aug(ival,v0[0]);
radj[v0[0]]=-1;
} else {
aug(ival,shsh);
radj[shsh]=v0[0];
aug(fdeg,v0[0]);
aug(fdeg,shsh,0);
hrad[shsh]=prad[velem[0]];
}
}
return;
}
ll xn = (l+r)/2;
vector<ll> v2;
for (ll i=0;i<M;i++) {
ll x = velem[i];
if (prad[x]>=xn) {
v2.push_back(ghsh(x,x+xn));
hrad[v2[i]]=xn;
aug(ival,v2[i],0);
aug(fdeg,v2[i],0);
} else {
v2.push_back(-1);
}
}
// unordered_map<ll,vector<ll>> vhsh;
// for (ll i=0;i<M;i++) {
// vhsh[v2[i]].push_back(velem[i]);
// }
// vector<ll> pr1;
// for (auto A0: vhsh) {
// if (A0.first!=-1) {
// process(A0.second,xn,r);
// pr1.push_back((A0.second)[0]);
// } else {
// for (ll x: A0.second) {
// pr1.push_back(x);
// }
// }
// }
// process(pr1,l,xn);
unordered_map<ll,vector<ll>> vhsh;
for (ll i=0;i<M;i++) {
vhsh[v2[i]].push_back(i);
}
vector<ll> pr1;
for (auto A0: vhsh) {
if (A0.first!=-1) {
vector<ll> vpr;
for (ll x: A0.second) {
vpr.push_back(velem[x]);
}
process(vpr,xn,r);
pr1.push_back((A0.second)[0]);
} else {
for (ll x: A0.second) {
pr1.push_back(x);
}
}
}
// cout << "processing back: l,r="<<l<<","<<r<<"\n";
// cout << "pr1 size="<<pr1.size()<<"\n";
unordered_map<ll,vector<ll>> vhsh1;
for (ll x: pr1) {
vhsh1[v0[x]].push_back(velem[x]);
}
for (auto A0: vhsh1) {
process(A0.second,l,xn);
}
}
queue<ll> q0;
int main() {
mt19937 gen((long long) new char);
aexp[0]=1;
for (ll i=0;i<Nm;i++) {
aexp[i+1]=(a*aexp[i])%p;
}
ios_base::sync_with_stdio(false); cin.tie(0);
string s; cin >> s;
string t="|";
N = s.length();
for (ll i=0;i<N;i++) {
t += s.substr(i,1);
t+="|";
}
N=t.length();
//cout << "N="<<N<<"\n";
for (ll i=0;i<N;i++) {
tval[i]=t[i];
}
// for (ll i=N;i<Nm;i++) {
// tval[i]=gen();
// }
phsh[0]=0;
for (ll i=0;i<Nm;i++) {
phsh[i+1]=(tval[i]+a*phsh[i])%p;
}
pihsh[0]=0;
for (ll i=0;i<Nm;i++) {
pihsh[i+1]=(tval[Nm-1-i]+a*pihsh[i])%p;
}
vector<ll> vall;
for (ll i=0;i<N;i++) { //get radii
vall.push_back(i);
ll rmin = 0;
ll rmax = min(i,N-1-i);
while (rmin<rmax) {
ll rt = (rmin+rmax+1)/2;
if (ghsh(i,i+rt)==gihsh(i-rt,i)) {
rmin = rt;
} else {
rmax = rt-1;
}
}
prad[i]=rmin;
//cout << "prad[i="<<i<<"]="<<prad[i]<<"\n";
}
process(vall,0,N+5);
//cout << "ghsh: "<<ghsh(1,2)<<"\n";
for (pii p0: fdeg) {
if (p0.second==0) {
q0.push(p0.first);
}
}
while (!q0.empty()) {
ll hv = q0.front(); q0.pop();
//cout << "process hv = "<<hv<<"\n";
ll rhv = hrad[hv];
ll ncnt = ival[hv];
//cout << "rhv,ncnt="<<rhv<<","<<ncnt<<"\n";
ans = max(ans,rhv*ncnt);
ll rad = radj[hv];
if (rad != -1) {
fdeg[rad]--;
if (fdeg[rad]==0) {
q0.push(rad);
}
aug(ival,rad,ival[hv]);
}
}
if (ghsh(0,N-1)==gihsh(0,N-1)) {
ans = max(ans,(N-1)/2);
}
cout << ans << "\n";
}
