#include <bits/stdc++.h>
using namespace std;
int main() {
  int n;
  cin >> n;
  string p, q;
  cin >> p >> q;
  int res = 0;
  if (n % 2 == 1 && p[n / 2] != q[n / 2]) res++;
  for (int i = 0; i < n / 2; i++) {
    char a = p[i];
    char b = p[n - i - 1];
    char c = q[i];
    char d = q[n - i - 1];
    if ((a == b && c == d) || (a == c && b == d) || (a == d && c == b))
      res += 0;
    else if (a == c || b == d || a == d || b == c || c == d)
      res += 1;
    else
      res += 2;
  }
  cout << res << endl;
  return 0;
}
