#include <bits/stdc++.h>   using namespace std;   string s1, s2;   int main() {     int n, i, j;     scanf( %d , &n);     cin >> s1 >> s2;     int ans = 0;     for (i = 0; i < (n / 2); i++) {       j = n - i - 1;       map<char, int> mp;       mp[s1[i]]++;       mp[s1[j]]++;       mp[s2[i]]++;       mp[s2[j]]++;       int len = mp.size();       if (len == 4)         ans += 2;       else if (len == 3)         ans += 1 + (s1[i] == s1[j]);       else if (len == 2)         ans += (mp[s1[i]] != 2);     }     if ((n % 2) && (s1[n / 2] != s2[n / 2])) ans++;     printf( %d , ans);     return 0;   }   