#include <iostream>

#include <cstdio>

#include <cstring>

#include <cmath>

#include <cstdlib>

#include <algorithm>

#define N 200005

#define to(x) ((x)+p[x])

#define from(x) ((x)-p[x])

using namespace std;

char s[N];

int n;

int p[N];

bool cmp(int a,int b){

	return from(a)<from(b);

}

int a[N];

int main(){

	scanf("%s",s+1);n=strlen(s+1)*2+1;

	for (int i=n;i;--i) s[i]=(i&1)?'*':s[i>>1];

	int M=0;p[0]=0;s[0]='@';s[n+1]='#';

	for (int i=1;i<=n;(M=to(i)>to(M)?i:M),i++)

		for (p[i]=(M+p[M]>i)*min(M+p[M]-i,p[2*M-i]);s[i+p[i]+1]==s[i-p[i]-1];++p[i]);

	int ans=0,j=0;

	for (int i=1;i<=n;++i) a[i]=i;

	sort(a+1,a+n+1,cmp);

	for (int i=1;i<=n;++i){

		while (to(j)<from(a[i])) ++j;

		ans=max(ans,to(a[i])-j*2+from(a[i]));

	}

	printf("%d\n",ans/2);

	return 0;

}