#include<bits/stdc++.h>
using namespace std;
int main(void){
  string s; cin>>s;
  int res=0,sz=s.size()-1;
  for(int i=0; i<sz; ++i) if(s[i]!=s[sz-i]) ++res,s[i]=s[sz-i];
  cout<<res;
  return 0;
}

### Prompt

Develop a solution in CPP 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
#include<bits/stdc++.h>
using namespace std;
int main(void){
  string s; cin>>s;
  int res=0,sz=s.size()-1;
  for(int i=0; i<sz; ++i) if(s[i]!=s[sz-i]) ++res,s[i]=s[sz-i];
  cout<<res;
  return 0;
}

```