#include <bits/stdc++.h>
using namespace std;
int main(){
	char s[102];
	int q=0;
	scanf("%s", s);
	for(int i = 0; i < strlen(s)/2; ++i){
		if(s[i] != s[strlen(s)-1-i]) q++;
	}
	cout<<q<<'\n';
}
### Prompt

Create a solution in cpp for 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 <bits/stdc++.h>
using namespace std;
int main(){
	char s[102];
	int q=0;
	scanf("%s", s);
	for(int i = 0; i < strlen(s)/2; ++i){
		if(s[i] != s[strlen(s)-1-i]) q++;
	}
	cout<<q<<'\n';
}
```