#include<bits/stdc++.h>

using namespace std;

int main(){

string s;

cin >> s;
int cnt=0;
for (int i = 0; i < s.size()/2; i++)
{
	if (s[i] != s[s.size()-1-i])
	{
		cnt++;	
	}
}

cout << cnt;
}
### Prompt

Develop a solution in cpp 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 cnt=0;
for (int i = 0; i < s.size()/2; i++)
{
	if (s[i] != s[s.size()-1-i])
	{
		cnt++;	
	}
}

cout << cnt;
}
```