#include<bits/stdc++.h>
using namespace std;

string s;
int Ans = 0;
int Check(string ss){
	if (ss.length()%2 == 1) return 0; 
	int l = 0 , r = ss.length()-1;
	while (l<r){
		if (ss[l] != ss[r]) return 0;
		l++; r--;
	}
	return 1;
}

string Cut(string ss){
	string sss;
	int n =ss.length();
	for (int i = 0; i < n/2; i++) sss+=ss[i];
	return sss;
}

void Dfs(string ss){
	int n = ss.length();
	if (n%2) return;
	if (Check(ss) == 0) return;
	ss = Cut(ss);
	Ans++; Dfs(ss);
}

int main(){
	cin>>s;
	Dfs(s);
	printf("%d",s.length()/(int)pow(2,Ans));
}