#include<bits/stdc++.h>
using namespace std;
string s,s1;
int a[400001],w[400001],ans,r,p[400001],id;
int ls(int x)
{
    return x<<1;
}
int rs(int x){
    return x<<1|1;
}
void pushup(int x)
{
    w[x]=max(w[ls(x)],w[rs(x)]);
}
void build(int l,int r,int x)
{
    if(l==r)
    {
        w[x]=a[l];
        return;
    }
    int mid=l+r>>1;
    build(l,mid,ls(x));
    build(mid+1,r,rs(x));
    pushup(x);
}
int query(int x,int l,int r,int L,int R)
{
    if(L<=l&&r<=R)
    {
        return w[x];
    }
    int mid=l+r>>1,ans=0;
    if(L<=mid)
        ans=max(ans,query(ls(x),l,mid,L,R));
    if(R>mid) ans=max(ans,query(rs(x),mid+1,r,L,R));
    return ans;
}
int main()
{
    cin>>s;
    s1="##";
    int ll=s.size()-1;
    for(int i=0;i<ll;i++)
    {
        s1+=s[i];
        s1+='#';
    }
    int len=s1.size()-1;
    for(int i=1;i<=len;i++)
    {
        if(r>i)
            p[i]=max(p[id*2-i],r-i);
        else p[i]=1;
        while(s1[i-p[i]]==s1[i+p[i]])
            p[i]++;
        if(i+p[i]>r)
        {
            id=i;
            r=i+p[i];
        }
    }
    //for(int i=1;i<=len;i++)cout<<p[i]<<" ";
    for(int i=1;i<=len;i++)
    {
        if(s1[i]!='#'||p[i]!=1)a[i-p[i]+1]=max(a[i-p[i]+1],i);
    }
    build(1,len,1);
    for(int i=1;i<=len;i++)
    {
        if(p[i]==1&&s1[i]=='#')continue;
        ans=max(query(1,1,len,i-p[i],i+p[i])-i,ans);
    }
    cout<<ans;
}