#define _USE_MATH_DEFINES
 
#include <iostream>
#include <iomanip>
#include <sstream>
 
#include <algorithm>
#include <cmath>
 
#include <string>
//#include <array>
#include <list>
#include <queue>
#include <vector>
#include <complex>
#include <set>
#include <map>
 
/////////
#define REP(i, x, n) for(int i = x; i < n; i++)
#define rep(i,n) REP(i,0,n)
#define P(p) cout<<(p)<<endl;
 
#define PII pair<int,int>
/////////
typedef long long LL;
typedef long double LD;
/////////
using namespace::std;
/////////

int main(void){
    std::cin.tie(0); 
    std::ios::sync_with_stdio(false);
    std::cout << std::fixed;//
    //cout << setprecision(16);//
	
	string S;
	cin>> S;
	int ma[50][50];
	int Len = S.size();

	rep(i,Len){
		rep(j,Len){
			if( S[i] == S[j] ){
				ma[i][j] = 1;
			}else{
				ma[i][j] = 0;
			}
		}
	}
	int ans = 0;
	int count;
	rep(i,Len)rep(j,Len){
		if( i == j ){
			ans = max( ans , 1 );
			continue;
		}
		int k = 0;
		count = 0;
		//Len-1
		while( i+k <Len && j-k >=i && ma[i+k][j-k] ){
			++count;
			++k;
		}
		
		if( abs(i-j)+1 < Len ){
			ans = max( ans , count );
		}
	}
	
	P(ans);
	return 0;
}