#include<sstream>
#include<iostream>
#include<cstdio>
#include<cstdlib>
#include<cstring>
#include<cmath>
#include<string>
#include<vector>
#include<set>
#include<map>
#include<queue>
#include<numeric>
#include<functional>
#include<algorithm>
#include<bitset>
using namespace std;
#define INF (1<<29)
#define rep(i,n) for(int i=0;i<(int)(n);i++)
#define all(v) v.begin(),v.end()
#define uniq(v) v.erase(unique(all(v)),v.end())
#define indexOf(v,x) (find(all(v),x)-v.begin())




int main(){
	string s;
	int dp[51]={};
	cin>>s;
	dp[0]=0;
	rep(i,s.size()){
		for(int j=i;j<s.size();j++){
			if(i==0&&j+1==s.size())break;
			int a=i,b=j;
			while(a<b){
				if(s[a]!=s[b])break;
				a++;b--;
			}
			if(a>=b){
				dp[j+1]=max(dp[j+1],max(dp[i],j-i+1));
			}
		}
	}
	cout<<dp[s.size()]<<endl;
	return 0;
}