#include <iostream>
#include <string>
#include <vector>
#include <queue>
#include <deque>
#include <algorithm>
#include <set>
#include <map>
#include <bitset>
#include <cmath>
#include <functional>
#include <iomanip>
#define vll vector<ll>
#define vvvl vector<vvl>
#define vvl vector<vector<ll>>
#define VV(a, b, c, d) vector<vector<d>>(a, vector<d>(b, c))
#define VVV(a, b, c, d) vector<vvl>(a, vvl(b, vll (c, d)));
#define re(c, b) for(ll c=0;c<b;c++)
#define rep(a,b,c) for(ll a=b;a<c;a++)
#define all(obj) (obj).begin(), (obj).end()
typedef long long int ll;
typedef long double ld;
using namespace std;

void get(vll &a){re(i,a.size()) scanf("%lld",&a[i]);}
void get(vvl &a){re(i,a.size()) re(j,a[0].size()) scanf("%lld",&a[i][j]);}
void print(vll &a){re(i,a.size()) cout<<a[i]<<(i==a.size()-1?"\n":" ");}
void print(vvl &a){re(i,a.size()) re(j,a[0].size())cout<<a[i][j]<<(j==a[0].size()-1?"\n":" ");}

vector<int> manacher(const string &s){
  int n = s.size(), c = 0;
  vector<int> rad(n);
  for(int r=0;r<n;r++){
    int l = c - (r - c);
    if(r + rad[l] < c + rad[c]) rad[r] = rad[l];
    else{
      int rr = c + rad[c];
      int rl = r - (rr - r);
      while(rl >= 0 && rr < n && s[rl] == s[rr]) rr++, rl--;
      rad[r] = rr - r;
      c = r;
    }
  }
  return rad;
}

string insert_dollar(const string &s){
  int n = s.size();
  string ret(n*2+1, '$');
  for(int i=0;i<n;i++) ret[i*2+1] = s[i];
  return ret;
}

bool is_palindrome(int l, int r, const vector<int> &rad){
  l = l * 2 + 1;
  r = (r - 1 ) * 2 + 1;
  int c = (l + r ) / 2;
  return r < c + rad[c];
}

int main(int argc, char const *argv[]) {
  string s;std::cin >> s;
  vector<int> v = manacher(insert_dollar(s));
  ll ans = 0;
  for(ll i=0;i<v.size();i++) if(v[i]-1<s.size()) ans = max(ans, (ll)v[i]-1);
  std::cout << ans << '\n';
  return 0;
}