#include <stdio.h>
#include <atcoder/all>
#include <bits/stdc++.h>
using namespace std;
using namespace atcoder;
using mint = modint998244353;
#define rep(i,n) for (int i = 0; i < (n); ++i)
#define Inf32 1000000001
#define Inf64 1000000000000000001

int main(){
	
	string s;
	cin>>s;
	int n = s.size();
	vector f(n,vector<bool>(n+1,false));
	rep(i,n){
		int l = i,r = i;
		f[i][1] = true;
		while(true){
			l--,r++;
			if(l<0||r>=n)break;
			if(s[l]!=s[r])break;
			f[l][r-l+1] = true;
		}
	}
	rep(i,n-1){
		if(s[i]!=s[i+1])continue;
		int l = i,r = i+1;
		f[i][2] = true;
		while(true){
			l--,r++;
			if(l<0||r>=n)break;
			if(s[l]!=s[r])break;
			f[l][r-l+1] = true;
		}
	}
	
	vector<int> dp(n+1,0);
	dp[0] = Inf32;
	rep(i,n){
		for(int j=1;j<=n;j++){
			if(i+j>n)break;
			if(!f[i][j])continue;
			dp[i+j] = max(dp[i+j],min(dp[i],j));
		}
	}
	cout<<dp[n]<<endl;
	
	return 0;
}