#include <bits/stdc++.h>
using namespace std;
void solve() {
  int n;
  string a, b;
  cin >> n >> a >> b;
  int ans = 0;
  for (int i = 0; i < n / 2; i++) {
    if (a[i] == a[n - i - 1] && b[i] == b[n - i - 1]) continue;
    int mn = 2;
    for (char c1 : {a[i], a[n - i - 1], b[i], b[n - i - 1]}) {
      for (char c2 : {a[i], a[n - i - 1], b[i], b[n - i - 1]}) {
        map<char, int> mp;
        for (char c : {c1, c2, b[i], b[n - i - 1]}) {
          mp[c]++;
        }
        if (mp.size() > 2) continue;
        bool ok = 0;
        if (mp.size() == 2) {
          for (auto x : mp) {
            if (x.second != 2) ok = 1;
          }
        }
        if (ok) continue;
        mn = min(mn, (c1 != a[i]) + (c2 != a[n - i - 1]));
      }
    }
    ans += mn;
  }
  if (n % 2 && a[n / 2] != b[n / 2]) ++ans;
  cout << ans << "\n";
}
int main() {
  ios::sync_with_stdio(0);
  cin.tie(0);
  cout.tie(0);
  int t = 1;
  while (t--) {
    solve();
  }
  return 0;
}
