Problem:
Score : 200 points

Problem Statement

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.

Sample Input 1

redcoder

Sample Output 1

1

For example, we can change the fourth character to o and get a palindrome redooder.

Sample Input 2

vvvvvv

Sample Output 2

0

We might need no hugs at all.

Sample Input 3

abcdabc

Sample Output 3

2

Solution in C++14 (GCC 5.4.1) (judge verdict: Wrong Answer)

//的場梨沙★担当
//結城晴★副担当
//日野茜★副担当
#include <vector>
#include <list>
#include <map>
#include <climits>
#include <set>
#include <unordered_set>
#include <unordered_map>
#include <deque>
#include <stack>
#include <bitset>
#include <algorithm>
#include <functional>
#include <numeric>
#include <utility>
#include <sstream>
#include <iostream>
#include <cmath>
#include <cstdlib>
#include <cctype>
#include <string.h>
#include <string>
#include <cstring>
#include <ctime>
#include <queue>
#include <random>
#include <cctype>
#include <complex>
#include <regex>
#include <unordered_map>
#include <string>
#include <algorithm>
#include <cctype>
#include <cstdio>
#include <cstdlib>
#include <iostream>
#include <iomanip>
#include <iostream>

using namespace std;

int main() {
    char M[100];
    char R[100];
    cin>>M;
    int k;
    k=strlen(M);
    int x=0;
    for(int n=0;n<k;n++){
        R[n]=M[k-1-n];
    }
    R[k]=0;
    for(int i=0;i<k-1;i++){
        if(M[i]!=R[i]){
            x++;
        }
        else{
            x=x+0;
        }
    }
    if(x==0) {
        cout << x << endl;
    }
    else{
        cout<<x-1<<endl;
    }
}