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

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

Please create a solution in Cpp 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 <bits/stdc++.h> 
using namespace std;

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