#include<cstdio>
#include<cstring>
int main()
{
	char a[105];
	scanf("%s",a);
	int n,m=0;
	n=strlen(a);
	for(int i=0;i<n/2;i++)
	{
		if(a[i]!=a[n-1-i])
		m++;
	}
	printf("%d\n",m);
}
### 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<cstdio>
#include<cstring>
int main()
{
	char a[105];
	scanf("%s",a);
	int n,m=0;
	n=strlen(a);
	for(int i=0;i<n/2;i++)
	{
		if(a[i]!=a[n-1-i])
		m++;
	}
	printf("%d\n",m);
}
```