#include <iostream>

#include <cstdio>

#include <cstring>

using namespace std;

const int maxn = 1e5 + ;

char S2[maxn*], str[maxn*];

int R[maxn*];

void Manacher(char* S){

    int L = strlen(S);

    for(int i = , j = ; i < *L; i += , j += ) S2[i] = '#', S2[j] = S[j/];

    S2[*L] = '#';

    int mx = -, id = -;

    for(int i = ; i < *L; i++){

        R[i] = mx-i >=  ? min(R[*id-i], mx-i+) : ;

        while(i+R[i] <= *L && S2[i+R[i]] == S2[i-R[i]]) R[i]++;

        if(i+R[i]- > mx) mx = i+R[i]-, id = i;

    }

}

int main()

{

    cin>>str;

    Manacher(str);

    int L = strlen(str), ans = ;

    //for(int i = 0; i < 2*L; i++) cout<<R[i]<<" "; cout<<endl;

    for(int i = ; i < *L; i += ) ans = max(ans, *(R[i]/-) + );

    for(int i = ; i < *L; i += ) ans = max(ans, R[i]-);

    cout<<ans<<endl;

    return ;

}