#include <bits/stdc++.h>

using namespace std;

int main()
{
	string s;
	cin >> s;
	int ans = 0;
	for(int i = 0 ; i < s.size() / 2 ; i++)
	   ans+=(s[i] != s[s.size() - i - 1]);
	
	cout << ans ;
}
### Prompt

Your challenge is to write a cpp solution to 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;

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