#include"iostream"
#include"stdio.h"
using namespace std;
const int maxn=3e6+5;
int P[maxn];
int f(string ss)
{
    int ans=-1;
    string s("#");
    for(int i=0;ss[i];i++)
    {
        s+=ss[i];
        s+="#";
    }
    P[0]=1;
    int id=1,mx=1;
    for(int i=1;s[i];i++)
    {
        if(mx>i)
        {
            P[i]=min(P[id*2-i],mx-i);
        }
        else 
        {
            P[i]=1;
        }
        while(s[i-P[i]]==s[i+P[i]]&&s[i-P[i]]&&s[i+P[i]])P[i]++;
        if(i+P[i]>=mx)
        {
            mx=i+P[i];
            id=i;
        }
        ans=max(ans,P[i]-1);

    }
    return ans;
}

int main()
{
    string s;
// freopen("a.txt","r",stdin); 
// freopen("1.txt","a",stdout);
    while(cin>>s)
    {
        cout<<f(s)<<"\n";
    }
}