#include<iostream>
using namespace std;

int main () {
string s;
cin >> s;

int i = 0, j = s.size() - 1;
int r = 0;
for(; i < j; i++, j--) {
if(s[i] != s[j]) r++;
}

cout << r << endl;

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<iostream>
using namespace std;

int main () {
string s;
cin >> s;

int i = 0, j = s.size() - 1;
int r = 0;
for(; i < j; i++, j--) {
if(s[i] != s[j]) r++;
}

cout << r << endl;

return 0;
}
```