#include <bits/stdc++.h>
#define syosu(x) fixed<<setprecision(x)
using namespace std;
typedef long long ll;
typedef unsigned long long ull;
typedef pair<int,int> P;
typedef pair<double,double> pdd;
typedef pair<ll,ll> pll;
typedef vector<int> vi;
typedef vector<vi> vvi;
typedef vector<double> vd;
typedef vector<vd> vvd;
typedef vector<ll> vl;
typedef vector<vl> vvl;
typedef vector<string> vs;
typedef vector<P> vp;
typedef vector<vp> vvp;
typedef vector<pll> vpll;
typedef pair<int,P> pip;
typedef vector<pip> vip;
const int inf=1<<30;
const ll INF=1ll<<60;
const double pi=acos(-1);
const double eps=1e-9;
const ll mod=1e6+7;
const int dx[4]={0,1,0,-1},dy[4]={1,0,-1,0};

int n;
string s;
vvi dp;

int main(){
	cin>>s;
	n=s.size();
	dp=vvi(n+1,vi(n+1,-1));
	for(int i=0;i<=n;i++) dp[i][i]=0;
	for(int k=1;k<=n;k++) for(int i=0;i<n-k+1;i++) for(int j=1;j<=k;j++){
		if(k==n&&i==0&&j==n) continue;
		string t=s.substr(i,j),t_=t;
		reverse(t.begin(),t.end());
		if(t==t_&&dp[i+j][i+k]!=-1) dp[i][i+k]=max({dp[i][i+k],j,dp[i+j][i+k]});
	}
	cout<<dp[0][n]<<endl;
}