#include <iostream>
#include <cstdio>
using namespace std;

string a;
int s;
int main() {
	int i, j;
	cin >> a;
	for(i=0, j=a.size()-1; i<j; i++, j--) s += a[i]!=a[j];
	cout << s;
	return 0;
}
### Prompt

Please formulate 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 <iostream>
#include <cstdio>
using namespace std;

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