#define _CRT_SECURE_NO_WARNINGS
#include<iostream>
#include<sstream>
#include<cstdio>
#include<cstdlib>
#include<cstring>
#include<climits>
#include<cmath>
#include<string>
#include<vector>
#include<set>
#include<map>
#include<queue>
#include<numeric>
#include<functional>
#include<algorithm>
#include<bitset>
#include<tuple>
#include<unordered_set>
#include<random>
#include<array>
#include<cassert>
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())




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

	string s;
	cin>>s;

	int ans = 0;
	rep(i,s.size()){
		int t=1;
		for (int j=1;i-j>=0 && i+j<s.size();j++){
			if (s[i-j]==s[i+j]){
				t+=2;
			}
		}
		ans = max(ans,t);
	}
	rep(i, s.size()-1){
		int t = 0;
		for (int j = 1; i - j + 1 >= 0 && i + j<s.size(); j++){
			if (s[i-j+1] == s[i+j]){
				t += 2;
			}
		}
		ans = max(ans, t);
	}


	cout<<ans<<endl;


	return 0;
}