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: Runtime Error)

#include<bits/stdc++.h>
using namespace std;
int main(){
    int N, ans;
    cin >> N;
    vector<int> b(N - 1);
    for(int i = 0; i < N - 1; i++){
        cin >> b[i];
    }
    for(int i = 0; i < N; i++){
        if(N == 2){
        ans += 2 * b[0];
        break;
        }
        if(N != 2){
            if(i == 0){
                ans += b[i];
            }
            else
            {
                ans += min(b[i], b[i + 1]);
            }
            
        }
    }
    cout << ans + b[N - 2] << endl;
}