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

int main()
{
	string s;
	int cs = 0;
	cin >> s;
	int n = s.size();
	for(int i = 0; i < n/2; i++)
		if(s[i] != s[n-(1+i)]) cs++;
	cout << cs;
	return 0;
}

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

int main()
{
	string s;
	int cs = 0;
	cin >> s;
	int n = s.size();
	for(int i = 0; i < n/2; i++)
		if(s[i] != s[n-(1+i)]) cs++;
	cout << cs;
	return 0;
}

```