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