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

In Cpp, your task is to solve 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>
int main(){
	int i,j,len,c=0;
	char s[101];
	scanf("%s",&s);
	len=strlen(s);
	for(i=0,j=len-1;i<j;i++,j--){
		if(s[i]!=s[j])
			c++;
	}
	printf("%d",c);
	
	return 0;
}
```