Problem:
Score : 200 points

Problem Statement

Takahashi loves palindromes. Non-palindromic strings are unacceptable to him. Each time he hugs a string, he can change one of its characters to any character of his choice.

Given is a string S. Find the minimum number of hugs needed to make S palindromic.

Constraints

S is a string consisting of lowercase English letters.

The length of S is between 1 and 100 (inclusive).

Input

Input is given from Standard Input in the following format:

S

Output

Print the minimum number of hugs needed to make S palindromic.

Sample Input 1

redcoder

Sample Output 1

1

For example, we can change the fourth character to o and get a palindrome redooder.

Sample Input 2

vvvvvv

Sample Output 2

0

We might need no hugs at all.

Sample Input 3

abcdabc

Sample Output 3

2

Solution in C++ (GCC 9.2.1) (judge verdict: Wrong Answer)

#include<bits/stdc++.h>
#define test int t; cin>>t; while(t--)
#define fast ios_base::sync_with_stdio(false); cin.tie(NULL); cout.tie(NULL);
#define pb push_back
#define mp make_pair
typedef long long ll;
using namespace std;
int main()
{
string s; cin>>s;
ll c=0,c1=0;
ll k=s.size();
for(ll i=0;i<k;i++)
{
    if(s[i]==s[k-i-1])
    {
        c++;
    }
    else
    {
        c1=1;
    }
}
if(c1){
ll n=k-c;
if(k%2==1)
cout<<n<<endl;
else
    cout<<n-1<<endl;
}
else
{
    cout<<0<<endl;
}
}