#include <bits/stdc++.h>
using namespace std;
int main() {
  int n;
  cin >> n;
  string a, b;
  cin >> a >> b;
  int ans = 0;
  if (n % 2 == 1 && a[n / 2] != b[n / 2]) ans++;
  for (int i = 0; i < n / 2; i++) {
    if (b[i] == b[n - i - 1]) {
      if (a[i] != a[n - i - 1] && (a[n - i - 1] != b[i] || a[i] != b[i])) ans++;
    } else {
      set<char> s;
      s.insert(b[i]);
      s.insert(b[n - i - 1]);
      if (a[i] == a[n - i - 1])
        if (s.count(a[i]))
          ans++;
        else
          ans += 2;
      else {
        if (!s.count(a[i])) ans++;
        if (!s.count(a[n - i - 1])) ans++;
      }
    }
  }
  cout << ans << endl;
}
