#include <iostream>
using namespace std;

char a[101];
int u=0,cvp=0;

int main(){
  cin>>a;
  for(int i=0;a[i];i++)u++;
	for(int i=0;i<u/2;i++)if(a[i]!=a[u-i-1])cvp++;  
  cout<<cvp;
 	return 0; 
}
### Prompt

Your task is to create 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 <iostream>
using namespace std;

char a[101];
int u=0,cvp=0;

int main(){
  cin>>a;
  for(int i=0;a[i];i++)u++;
	for(int i=0;i<u/2;i++)if(a[i]!=a[u-i-1])cvp++;  
  cout<<cvp;
 	return 0; 
}
```