hackerearcth palindrome

#include <bits/stdc++.h>
using namespace std;
#define ll long long
#define test int t; cin>>t; for(int cs=1;cs<=t;cs++)
int main()
{
   ios_base::sync_with_stdio(0);
   cin.tie(0);cout.tie(0);

   string a;
   ll c,d,e,f=0,i,j,k,l;
   cin>>a;

   for(i=0;i<a.size();i++)
   {
       if(a[i]==a[0])
       {
           f++;
       }
   }
   if(f==a.size()) cout<<0<<endl;
   else
   {
       string c;
       c=a;
       reverse(c.begin(),c.end());
       if(c==a) cout<<a.size()-1<<endl;
       else cout<<a.size()<<endl;
   }

   return 0;
}