#include <stdio.h>
#include <string.h>
char txt[101];
int main(){
	scanf("%s",txt);
	int len = strlen(txt);
	int cnt = 0;
	for(int i=0;i<=len-1-i;i++) cnt+=txt[i]!=txt[len-1-i];
	printf("%d",cnt);
}
### Prompt

Generate 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 <stdio.h>
#include <string.h>
char txt[101];
int main(){
	scanf("%s",txt);
	int len = strlen(txt);
	int cnt = 0;
	for(int i=0;i<=len-1-i;i++) cnt+=txt[i]!=txt[len-1-i];
	printf("%d",cnt);
}
```