#include <bits/stdc++.h>
using namespace std;
const int oo = (int)1e9;
const double PI = 2 * acos(0.0);
const double eps = 1e-7;
inline complex<int> operator-(const complex<int> &a, const complex<int> &b) {
  return {a.real() - b.real(), a.imag() - b.imag()};
}
int dx[] = {1, 0, 0, -1, -1, -1, 1, 1};
int dy[] = {0, 1, -1, 1, 1, -1, 1, -1};
const int MOD = 1e9 + 7;
int main() {
  int n;
  string a, b;
  cin >> n;
  cin >> a >> b;
  int ans = 0;
  for (int i = 0; i < n / 2; i++) {
    int add = 2;
    bool f1 = 0, f2 = 0;
    if (a[i] == b[i]) f1 = 1;
    if (a[n - i - 1] == b[n - i - 1]) f2 = 1;
    if (f1 && f2) add = min(add, 0);
    if (f1 || f2) add = min(add, 1);
    if (a[i] == a[n - i - 1]) {
      if (b[i] != b[n - i - 1])
        add = min(add, 2);
      else
        add = min(add, 0);
    } else {
      if (b[i] == b[n - i - 1])
        add = min(add, 1);
      else
        add = min(add, 2);
    }
    f1 = f2 = 0;
    if (a[i] == b[n - i - 1]) f1 = 1;
    if (a[n - i - 1] == b[i]) f2 = 1;
    if (f1 && f2) add = min(add, 0);
    if (f1 || f2) add = min(add, 1);
    ans += add;
  }
  if (n % 2 == 1 && a[n / 2] != b[n / 2]) ans++;
  cout << ans << endl;
}
