#include <bits/stdc++.h>
char s[100005], s1[100005];
int n, ans;
int c[5];
int main() {
  scanf("%d", &n);
  scanf("%s", s);
  scanf("%s", s1);
  ans = 0;
  c[0] = -1;
  for (int i = 1; i <= n / 2; i++) {
    c[1] = s[i - 1] - 'a';
    c[2] = s[n - i] - 'a';
    c[3] = s1[i - 1] - 'a';
    c[4] = s1[n - i] - 'a';
    std::sort(c + 1, c + 5);
    int tot = 0;
    int ta = 0;
    for (int j = 1; j <= 4; j++) {
      if (c[j] != c[j - 1]) ++tot;
      if (c[j] == s[i - 1] - 'a') ++ta;
    }
    if (tot == 2) {
      if (c[1] != c[2] || c[3] != c[4]) ans += (ta != 2);
    } else if (tot == 1)
      ans += 0;
    else if (tot == 3)
      ans += 1 + (s[i - 1] == s[n - i]);
    else
      ans += 2;
  }
  if (n % 2) {
    if (s[n / 2] != s1[n / 2]) ++ans;
  }
  printf("%d", ans);
  return 0;
}
