#include <bits/stdc++.h>
using namespace std;
using ll = int; using pii = pair<ll,ll>;
const __int128 a = 1234567; const __int128 p = 337190719854678689; //hash values
ll ans = 0;
const ll Nm = 6e5+5; ll N;
__int128 aexp[Nm+1];
__int128 phsh[Nm+1];
__int128 pihsh[Nm+1];
ll tval[Nm];
ll prad[Nm]; //permutation radius
long long ghsh(ll l, ll r) { //[l,r]
__int128 v = phsh[r+1]-aexp[r+1-l]*phsh[l];
v = (v+p*(-v/p+2))%p;
return v;
}
long long gihsh(ll l0, ll r0) { //[l,r]
ll l = Nm-1-r0; ll r = Nm-1-l0;
__int128 v = pihsh[r+1]-aexp[r+1-l]*pihsh[l];
v = (v+p*(-v/p+2))%p;
return v;
}
struct Node {
int fdeg = 0;
int ival = 0;
int xp; //x position
int hrad;
ll radj=-1;
long long hashv;
Node(ll x0, ll rad0) {
xp = x0; hrad = rad0;
if (hrad<=prad[x0]) {
hashv = ghsh(x0,x0+hrad);
} else {
hashv = -1;
}
}
};
vector<Node> MEM;
ll process(vector<ll> velem, vector<ll> memf, ll l, ll r) { //return location of root
//vector of coordinates, vector of (at v1), left, right
// cout << "process: l,r="<<l<<","<<r<<"\nvelem:\n";
// for (ll x: velem) {
// cout << x << " ";
// }
// cout << "\n";
if (velem.size()==0) {
assert(1==2);
return -1;
}
ll M = velem.size();
//memf stores v1
if ((r-1)==l) { //process
ll mem0 = MEM.size();
MEM.push_back(Node(velem[0],l));
for (ll i=0;i<M;i++) {
if (memf[i]==-1) {
MEM[mem0].ival++;
//cout << "add source at x0,l="<<velem[0]<<","<<l<<"\n";
} else {
MEM[memf[i]].radj=mem0;
MEM[mem0].fdeg++;
}
}
return mem0;
}
if (M==1) {
ll mem0 = MEM.size();
MEM.push_back(Node(velem[0],l));
if (memf[0]!=-1) {
MEM[memf[0]].radj=mem0;
MEM[mem0].fdeg++;
} else {
ll x0 = velem[0]; ll rad0 = prad[velem[0]];
if (l==rad0) {
MEM[mem0].ival++;
//cout << "add source at x0,l="<<x0<<","<<l<<"\n";
} else {
MEM.push_back(Node(x0,rad0));
//cout << "create source node: x0,rad0="<<x0<<","<<rad0<<"\n";
MEM[MEM.size()-1].ival++;
MEM[MEM.size()-1].radj=mem0;
MEM[mem0].fdeg++;
}
}
return mem0;
}
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));
} else {
v2.push_back(-1);
}
}
unordered_map<ll,vector<int>> vhsh;
for (ll i=0;i<M;i++) {
vhsh[v2[i]].push_back(i);
}
vector<pair<ll,vector<int>>> vhshN;
for (auto A0: vhsh) {
vhshN.push_back(A0);
}
vhsh.clear();
vector<ll> xloc,mloc;
for (auto A0: vhshN) {
if (A0.first==-1) {
for (ll x: A0.second) {
xloc.push_back(velem[x]);
mloc.push_back(-1);
}
} else {
xloc.push_back(velem[(A0.second)[0]]);
vector<ll> xloc2,mloc2;
for (ll x: A0.second) {
xloc2.push_back(velem[x]);
mloc2.push_back(memf[x]);
}
mloc.push_back(process(xloc2,mloc2,xn,r));
}
}
return process(xloc,mloc,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;
vector<ll> vm1(N,-1);
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,vm1,-1,N+5);
//cout << "ghsh: "<<ghsh(1,2)<<"\n";
for (ll POS=0;POS<MEM.size();POS++) {
if (MEM[POS].fdeg==0) {
q0.push(POS);
}
}
while (!q0.empty()) {
ll madd = q0.front(); q0.pop();
ans = max((ll)ans,(ll)MEM[madd].ival*MEM[madd].hrad);
//cout << "ival,hrad="<<MEM[madd].ival<<","<<MEM[madd].hrad<<"\n";
ll rad = MEM[madd].radj;
if (rad != -1) {
//fdeg[rad]--;
MEM[rad].fdeg--;
if (MEM[rad].fdeg==0) {
q0.push(rad);
}
assert(MEM[rad].fdeg>=0);
//aug(ival,rad,ival[hv]);
MEM[rad].ival+=MEM[madd].ival;
}
}
if (ghsh(0,N-1)==gihsh(0,N-1)) {
ans = max(ans,(N-1)/2);
}
cout << ans << "\n";
}
