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

int main() {
	string S; cin >> S;
	int r = 0;
	for(int i = 0; i * 2 < S.size(); i++) if(S[i] != S[S.size() - i - 1]) r++;
	cout << r;
}

### Prompt

Please provide a cpp coded solution to the problem described below:

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

int main() {
	string S; cin >> S;
	int r = 0;
	for(int i = 0; i * 2 < S.size(); i++) if(S[i] != S[S.size() - i - 1]) r++;
	cout << r;
}

```