据说是一些版子
bool IsPrime[1000010];
int Prim[1000010];
int euler_prime(int n){
int num = 0, j;
for(int i = 2; i <= n; i ++){
if(!IsPrime[i])
Prim[num ++] = i;
for(j = 0; j < num; j ++){
if(i * Prim[j] > n)
break;
IsPrime[i * Prim[j]] = true;
if(i % Prim[j] == 0)
break;
}
}
//for(int i = 0; i < num; i ++){
// cout << Prim[i] << endl;
//}
}/*欧拉筛*/
#include <bits/stdc++.h>
//大素数的Miller-Rabin算法
using namespace std;
typedef long long ll;
//利用二进制计算a*b%mod
ll multiMod(ll a,ll b,ll mod){
ll ret = 0LL;
a %= mod;
while( b ){
if ( b & 1LL ) ret = ( ret + a ) % mod, --b;
b >>= 1LL;
a = ( a + a ) % mod;
}
return ret;
}
//计算a^b%mod
ll powerMod(ll a,ll b,ll mod){
ll ret = 1LL;
a %= mod;
while( b ){
if ( b & 1LL ) ret = multiMod(ret,a,mod),--b;
b >>= 1LL;
a = multiMod(a,a,mod);
}
return ret;
}
//Miller-Rabin测试,测试n是否为素数
bool Miller_Rabin(ll n,int repeat){
if ( 2LL == n || 3LL == n ) return true;
if ( !( n & 1LL ) ) return false;
//将n分解为2^s*d
ll d = n - 1LL;
int s = 0;
while( !( d & 1LL ) ) ++s, d>>=1LL;
srand((unsigned)time(0));
for(int i=0;i<repeat;++i){//重复repeat次
ll a = rand() % ( n - 3 ) + 2;//取一个随机数,[2,n-1)
ll x = powerMod(a,d,n);
ll y = 0LL;
for(int j=0;j<s;++j){
y = multiMod(x,x,n);
if ( 1LL == y && 1LL != x && n-1LL != x ) return false;
x = y;
}
if ( 1LL != y ) return false;
}
return true;
}
int main(){
ll n;
while(~scanf("%lld",&n))
{
if ( Miller_Rabin(n,3) ) {
printf("Yes\n");
} else {
printf("No\n");
}
}
return 0;
}
struct hash_table{
ull seed;
ull Hash[maxn],temp[maxn];
void Set(ull num){
seed=num;
}
void work(char *s,int n){
temp[0]=1;
Hash[0]=0;
for(int i=1;i<=n;i++)temp[i]=temp[i-1]*seed;
for(int i=1;i<=n;i++)Hash[i]=(Hash[i-1]*seed+(s[i]-'a'));
}
ull get(int l,int r){
return Hash[r]-Hash[l-1]*temp[r-l+1];
}
}h;
#include <cstdio>
#include <cstring>
#include <iostream>
#include <algorithm>
using namespace std;
const int maxn = 1e6+5;
struct splaytree{
int date;
}spt[maxn];
int fth[maxn],sn[maxn][2],num[maxn],size[maxn];
int sz,rt;
inline void clr(int x) {
sn[x][0] = sn[x][1] = fth[x] = size[x] = num[x] = spt[x].date = 0;
}
inline void create(int x) { sz++; sn[x][0] = sn[x][1] = fth[x] = 0; num[x] = size[x] = 1; }
inline int whs(int x) { return sn[fth[x]][1] == x; }
inline void setson(int son,int f,int w) {
if ( son != 0 ) fth[son] = f;
if ( f != 0 ) sn[f][w] = son;
}
inline void maintain(int x) {
size[x] = size[sn[x][0]] + size[sn[x][1]] + num[x];
}
inline void rotate(int x) {
int f = fth[x]; int ff = fth[f]; int w = whs(x); int wf = whs(f);
int p = sn[x][!w];
setson(p,f,w); setson(x,ff,wf); setson(f,x,!w);
maintain(f); maintain(x);
}
inline void splay(int x) {
for (;fth[x];rotate(x)) {
if ( fth[fth[x]] && whs(fth[x]) == whs(fth[fth[x]]))
rotate(fth[x]);
}
rt = x;
}
inline void insert(int x) {
if ( rt == 0 ) {
create(x); rt = sz; return;
}
int now = rt , f = 0;
while(true) {
if ( x == spt[now].date ) {
num[now]++; maintain(now); maintain(f); splay(now); break;
} f = now; now = sn[now][spt[now].date < x];
if(now == 0 ) {
create(x); fth[sz] = f;
sn[f][spt[f].date<x] = sz; spt[sz].date = x;
maintain(f); splay(sz);
break;
}
}
}
inline int find(int x) {
int ans = 0,now = rt;
while (true) {
if ( x < spt[now].date ) now = sn[now][0];
else {
ans += sn[now][0] ? size[sn[now][0]] : 0;
if ( x == spt[now].date ) {
splay(now); return ans + 1;
} ans += num[now]; now = sn[now][1];
}
}
}
inline int Kth(int x) {
int now = rt;
while(1){
if(sn[now][0] && x <= size[sn[now][0]]) now = sn[now][0];
else{
int tmp = (sn[now][0] ? size[sn[now][0]] :0) + num[now];
if(x <= tmp) return spt[now].date;
x -= tmp;
now = sn[now][1];
}
}
}
inline int pre() {
int now = sn[rt][0];
while(sn[now][1]) now = sn[now][1];
return now;
}
inline int nxt() {
int now = sn[rt][1];
while(sn[now][0]) now = sn[now][0];
return now;
}
int main() {
int n,op,x;
return 0;
}
#include <iostream>
#include <cstdio>
#include <cstring>
#include <algorithm>
#include <cmath>
#include <queue>
#include <map>
using namespace std;
const int N = 200010;
char s[N], str[N*2];
int p[N*2];
int manacher()
{
int i;
for(i = 1; s[i]; i++)
str[i*2] = s[i], str[i*2+1] = '#';
str[0] = '?', str[1] = '#', str[i*2] = '\0';
int res = 0, k = 0, maxk = 0;
for(int i = 2; str[i]; i++)
{
p[i] = i < maxk ? min(maxk - i, p[2*k-i]) : 1;
while(str[i-p[i]] == str[i+p[i]]) p[i]++;
if(p[i] + i > maxk)
k = i, maxk = i + p[i];
res = max(res, p[i]); // manacher
}
return res - 1;
}
int main()
{
while(~ scanf(" %s", s + 1))
printf("%d\n", manacher());
return 0;
}