//lg 3805
//Copyright yeyou26
#include<bits/stdc++.h>
using namespace std;

int d[(int)1e8];
char ipt[(int)1e8];
char c[(int)1e8];
int n;

void init();
void Manacher();
void print();

int main()
{
    freopen("working.in","r",stdin);
    freopen("working.out","w",stdout);
    init();
    Manacher();
    print();
    return 0;
}

//Function Implementation

void init()
{
    cin>>(ipt+1);
    c[0]='$';
    int k=1;
    c[k]='#';
    n=strlen(ipt+1);
    for(int i=1;i<=n;i++)
    {
        c[++k]=ipt[i],c[++k]='#';
    }
    n=k;
}

void Manacher()
{
    d[1]=1;
    for(int i=2,l,r=1;i<=n;i++)
    {
        if(i<=r) d[i]=min(d[r-i+l],r-i+1);
        while(c[i+d[i]]==c[i-d[i]]) d[i]++;
        if(r<i+d[i]-1) r=i+d[i]-1,l=i-d[i]+1;
    }
}

void print()
{
    int mx=-1;
    for(int i=1;i<=n;i++)
    {
        mx=max(mx,d[i]);
    }
    cout<<mx-1;
}