#include <bits/stdc++.h>
using namespace std;
int main() {
  int n, ans = 0;
  cin >> n;
  string a, b;
  cin >> a;
  cin >> b;
  if (n % 2) {
    ans = (a[(n / 2)] != b[(n / 2)]);
  }
  vector<set<char> > v;
  for (int i = 0; i < (n / 2); i++) {
    set<char> s;
    s.insert(a[i]);
    s.insert(b[i]);
    s.insert(a[n - i - 1]);
    s.insert(b[n - i - 1]);
    v.push_back(s);
  }
  for (int i = 0; i < v.size(); i++) {
    if (v[i].size() == 4) {
      ans += 2;
    } else if (v[i].size() == 3) {
      ans += 1 + (a[i] == a[n - i - 1]);
    } else if (v[i].size() == 2) {
      char c1 = a[i], c2 = a[n - i - 1], c3 = b[i], c4 = b[n - i - 1];
      if (c1 == c2 && c2 == c3 && c1 != c4) ans++;
      if (c1 == c2 && c2 == c4 && c1 != c3) ans++;
      if (c1 == c3 && c3 == c4 && c1 != c2) ans++;
      if (c2 == c3 && c3 == c4 && c2 != c1) ans++;
    }
  }
  cout << ans << '\n';
}
