#include <bits/stdc++.h>
using namespace std;

int main() {
	// your code goes here

string a;
cin>>a;
int c=0;
for(int i=0,j=a.size()-1;i<j;j--,i++){
if(a[i] != a[j]) c++;
}
 cout<<c<<"\n";
	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 <bits/stdc++.h>
using namespace std;

int main() {
	// your code goes here

string a;
cin>>a;
int c=0;
for(int i=0,j=a.size()-1;i<j;j--,i++){
if(a[i] != a[j]) c++;
}
 cout<<c<<"\n";
	return 0;
}
```