#include <bits/stdc++.h>
using namespace std;
long long t = 1, tt;
void solve() {
  long long n;
  cin >> n;
  string a, b;
  cin >> a >> b;
  if (n == 1) {
    if (a == b)
      cout << 0;
    else
      cout << 1;
    return;
  }
  long long ans = 0;
  for (long long i = 0; i < n / 2; i += 1) {
    set<char> ss;
    map<char, long long> mapa;
    ss.insert(a[i]);
    mapa[a[i]]++;
    ss.insert(a[n - i - 1]);
    mapa[a[n - i - 1]]++;
    ss.insert(b[i]);
    mapa[b[i]]++;
    ss.insert(b[n - i - 1]);
    mapa[b[n - i - 1]]++;
    if (int((ss).size()) == 4) ans += 2;
    if (int((ss).size()) == 3) {
      if (a[i] == a[n - i - 1])
        ans += 2;
      else
        ans += 1;
    }
    if (int((ss).size()) == 2) {
      if (mapa[a[i]] == 1 || mapa[a[i]] == 3) ans += 1;
    }
  }
  if (n % 2 == 1) {
    if (a[n / 2] != b[n / 2]) ans += 1;
  }
  cout << ans;
}
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(0);
  cout.tie(0);
  tt = t;
  while (t--) solve();
  return 0;
}
