#include <bits/stdc++.h>

using namespace std;

//typedef
//------------------------------------------
typedef vector<int> VI;
typedef vector<VI> VVI;
typedef vector<string> VS;
typedef pair<int, int> PII;
typedef long long LL;

//container util
//------------------------------------------
#define ALL(a)  (a).begin(),(a).end()
#define RALL(a) (a).rbegin(), (a).rend()
#define PB push_back
#define MP make_pair
#define SZ(a) int((a).size())
#define EACH(i,c) for(typeof((c).begin()) i=(c).begin(); i!=(c).end(); ++i)
#define EXIST(s,e) ((s).find(e)!=(s).end())
#define SORT(c) sort((c).begin(),(c).end())

//repetition
//------------------------------------------
#define FOR(i,a,b) for(int i=(a);i<(b);++i)
#define REP(i,n)  FOR(i,0,n)

//constant
//--------------------------------------------
const double EPS = 1e-10;
const double PI  = acos(-1.0);

bool ispalin(string s){
  for(int i=0;i<SZ(s);++i)
	if(s[i] != s[SZ(s)-1-i])
	  return false;
  return true;
}

int main(){
  cin.tie(0);
  ios_base::sync_with_stdio(false);

  string S; cin >> S;
  int dp[100][100];
  fill((int*)dp, (int*)dp+100*100, 0);
  int N = SZ(S);
  for(int l=1;l<=N;++l){
	for(int i=0;i+l<=N;++i){
	  int e = i + l;
	  if(l < N && ispalin(S.substr(i,l))) dp[i][e] = l;
	  for(int k=i+1;k<e;++k){
		dp[i][l] = max(dp[i][l], max(dp[i][k], dp[k][e]));
	  }
	}
  }
  cout << dp[0][N] << endl;
  
  return 0;
}