#include <bits/stdc++.h>
using namespace std;
int32_t main() {
  long long n;
  cin >> n;
  string a, b;
  cin >> a >> b;
  long long rres = 0;
  if (n % 2 == 1) {
    if (a[(n / 2)] != b[(n / 2)]) rres++;
  }
  for (long long i = 0; i < n / 2; i++) {
    char a1 = a[i];
    char a2 = a[n - i - 1];
    char b1 = b[i];
    char b2 = b[n - i - 1];
    if (a1 > a2) swap(a1, a2);
    if (b1 > b2) swap(b1, b2);
    if (b1 == b2) {
      if (a1 != a2) {
        rres++;
      }
    } else if (a1 == a2) {
      if (a1 == b1 || a1 == b2)
        rres++;
      else
        rres += 2;
    } else if (a1 == b1) {
      if (a2 != b2) rres++;
    } else if (a1 == b2) {
      if (a2 != b1) rres++;
    } else if (a2 == b1 || a2 == b2) {
      rres++;
    } else {
      rres += 2;
    }
  }
  cout << rres << endl;
}
