#include <iostream>
#include <cstring>
using namespace std;
int main()
{
char sir[256];
cin.getline(sir,256);
int n=strlen(sir), m=0, ok=1, i;
while (n%2==0 && ok)
{
for (i=0; i<n/2; ++i)
{
if (sir[i]!=sir[n-1-i]) { ok=0; break; }
}
if (ok) { ++m; n/=2; }
}
cout <<m;
return 0;
}