#include <bits/stdc++.h>
using namespace std;
string a, b;
int n;
int f(char a, char b, char c, char d) {
  map<char, int> mp;
  mp[a]++;
  mp[b]++;
  mp[c]++;
  mp[d]++;
  vector<int> t;
  for (auto it : mp) t.push_back(it.second);
  if (t.size() == 1) return 0;
  if (t.size() == 2) {
    if (t[0] == t[1])
      return 0;
    else
      return 1;
  }
  if (t.size() == 4) return 2;
  if (t.size() == 3) {
    if (a == b)
      return 2;
    else
      return 1;
  }
}
int main() {
  ios::sync_with_stdio(false);
  cin.tie(0);
  int n;
  while (cin >> n) {
    cin >> a;
    cin >> b;
    int ans = 0;
    for (int i = 0, j = n - 1; i <= j; i++, j--) {
      ans += f(a[i], a[j], b[i], b[j]);
    }
    if (a[n / 2] != b[n / 2] && n % 2 == 1) ans += 1;
    cout << ans << endl;
  }
  return 0;
}
