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

string a,r;
int ans;

int main()
{
	cin>>a;

	r=a;
	reverse(r.begin(),r.end());
	for(int i=0;i<a.size()/2;i++)
		if(a[i]!=r[i]) ans++;
	cout<<ans;
}
### Prompt

Create a solution in CPP for the following problem:

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;

string a,r;
int ans;

int main()
{
	cin>>a;

	r=a;
	reverse(r.begin(),r.end());
	for(int i=0;i<a.size()/2;i++)
		if(a[i]!=r[i]) ans++;
	cout<<ans;
}
```