#include<bits/stdc++.h>

using namespace std;
int main()
{
 string s;
 cin>>s;
 int n=s.size();
 int i,ans=0;
 for(i=0;i<n;i++)
 {
  if(s[i]!=s[n-i-1]) ans++;
  }
  cout<<ans/2;

 }












### Prompt

Please provide a Cpp coded solution to the problem described below:

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.

Examples

Input

redcoder


Output

1


Input

vvvvvv


Output

0


Input

abcdabc


Output

2

### Response

```cpp
#include<bits/stdc++.h>

using namespace std;
int main()
{
 string s;
 cin>>s;
 int n=s.size();
 int i,ans=0;
 for(i=0;i<n;i++)
 {
  if(s[i]!=s[n-i-1]) ans++;
  }
  cout<<ans/2;

 }












```