#include <bits/stdc++.h>
const int N = 1e6 + 5, MOD = 998244353;
using namespace std;
string a, b;
int n, ans;
int wa(int x) {
  set<char> s;
  map<char, int> occ;
  s.insert(a[x]), s.insert(b[x]), s.insert(a[n - x - 1]),
      s.insert(b[n - x - 1]);
  occ[a[x]]++;
  occ[b[x]]++, occ[a[n - x - 1]]++, occ[b[n - x - 1]]++;
  if (((int)(s).size()) == 1) return 0;
  int ret = 0;
  for (auto p : occ) {
    ret += (p.second % 2);
  }
  if (((int)(s).size()) == 2 && ret) ret--;
  if (((int)(s).size()) == 3) {
    if (occ[a[x]] == occ[a[n - x - 1]] && occ[a[x]] == 2)
      return ret;
    else
      ret--;
  }
  if (((int)(s).size()) == 4) ret -= 2;
  return ret;
}
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);
  cin >> n >> a >> b;
  for (int i = 0; i < n / 2; i++) {
    ans += wa(i);
  }
  if (n % 2) ans += (a[n / 2] != b[n / 2]);
  cout << ans << "\n";
}
