#include <bits/stdc++.h>
using namespace std;
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);
  cout.tie(NULL);
  long long i, j, n, t = 1, k = 0, cnt = 0, mini = LLONG_MAX, maxi = LLONG_MIN,
                     ans = 0;
  long long m;
  cin >> n;
  string a, b;
  cin >> a >> b;
  for (i = 0; i < (n + 1) / 2; i++) {
    if (n % 2 == 1 && i == n / 2) {
      if (a[i] != b[i]) ans++;
      continue;
    }
    set<char> s;
    s.insert(a[i]);
    s.insert(b[i]);
    s.insert(a[n - 1 - i]);
    s.insert(b[n - 1 - i]);
    map<char, long long> mm;
    mm[a[i]]++;
    mm[a[n - 1 - i]]++;
    mm[b[i]]++;
    mm[b[n - 1 - i]]++;
    if (s.size() == 2) {
      set<long long> p;
      for (auto it : mm) p.insert(it.second);
      if (p.size() > 1) ans += 1;
    }
    if (s.size() == 4) ans += 2;
    if (s.size() == 3) {
      if (a[i] == a[n - 1 - i])
        ans += 2;
      else
        ans++;
    }
  }
  return cout << ans, 0;
  return 0;
}
