#include<iostream>
using namespace std;
int i, ans;
string s;
int main()
{
	cin>>s;
	for(i=0; i<s.size()/2; i++)
	{
		if(s[i]!=s[s.size()-i-1])
		{
			ans++;
		}
	}
	cout<<ans;
	return 0;
}

### Prompt

Your task is to create 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>
using namespace std;
int i, ans;
string s;
int main()
{
	cin>>s;
	for(i=0; i<s.size()/2; i++)
	{
		if(s[i]!=s[s.size()-i-1])
		{
			ans++;
		}
	}
	cout<<ans;
	return 0;
}

```