#include <bits/stdc++.h>
using namespace std;
int dx[] = {0, 1, 0, -1};
int dy[] = {1, 0, -1, 0};
int ddx[] = {1, 0};
int ddy[] = {1, 1};
int n;
string a, b;
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);
  cin >> n;
  cin >> a;
  cin >> b;
  long long int ans = 0;
  for (int i = 0; i < int(a.size()) / 2; i++) {
    int j = n - i - 1;
    if (a[i] == a[j] and b[i] == b[j])
      continue;
    else if (a[i] == b[j] and b[i] == a[j])
      continue;
    if (a[i] != b[i]) {
      if (a[j] != b[j]) {
        if (a[i] == a[j])
          ans += 2;
        else if (b[i] == b[j])
          ans++;
        else if (a[i] == b[j])
          ans++;
        else if (b[i] == a[j])
          ans++;
        else
          ans += 2;
      } else {
        ans++;
      }
    } else if (a[j] != b[j]) {
      ans++;
    }
  }
  if (int(a.size()) % 2 != 0)
    if (a[int(a.size()) / 2] != b[int(a.size()) / 2]) ans++;
  cout << ans << "\n";
  return 0;
}
