#include<cstring>
#include<iostream>
int main(){char s[100];scanf("%s",s);int l=strlen(s);int b=0;for(int i=0;i<l/2;++i)b+=(s[i]!=s[l-i-1]);printf("%d",b);}
### Prompt

Construct a cpp code solution to the problem outlined:

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<cstring>
#include<iostream>
int main(){char s[100];scanf("%s",s);int l=strlen(s);int b=0;for(int i=0;i<l/2;++i)b+=(s[i]!=s[l-i-1]);printf("%d",b);}
```