#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 && a[n / 2] != b[n / 2]) ans++;
  for (int i = 0; i < n / 2; i++) {
    set<char> s;
    s.insert(a[i]);
    s.insert(b[i]);
    s.insert(a[n - 1 - i]);
    s.insert(b[n - 1 - i]);
    if (s.size() < 2 || a[i] == b[i] && a[n - i - 1] == b[n - i - 1] ||
        a[i] == a[n - i - 1] && b[i] == b[n - i - 1] ||
        a[i] == b[n - i - 1] && b[i] == a[n - i - 1])
      continue;
    else if (s.size() == 4 ||
             (s.size() == 3 && b[i] != b[n - 1 - i] && a[i] == a[n - i - 1]))
      ans += 2;
    else
      ans += 1;
  }
  cout << ans << endl;
}
