#include <bits/stdc++.h>
using namespace std;
const int maxn = 100010;
int n;
char a[maxn], b[maxn];
int f(char a, char b, char c, char d) {
  int s[4];
  s[0] = a - 'a';
  s[1] = b - 'a';
  s[2] = c - 'a';
  s[3] = d - 'a';
  sort(s, s + 4);
  int ans = 1;
  for (int i = 1; i < 4; i++) {
    if (s[i] != s[i - 1]) ans++;
  }
  return ans;
}
int main() {
  scanf("%d", &n);
  scanf("%s%s", &a, &b);
  if (n % 2 == 0) {
    int i, j, ans = 0;
    for (int i = 0; i < n / 2; i++) {
      j = n - i - 1;
      int kind = f(a[i], a[j], b[i], b[j]);
      if (kind == 1)
        continue;
      else if (kind == 2) {
        int cnt = 1;
        int tmp[4];
        tmp[0] = a[i] - 'a';
        tmp[1] = a[j] - 'a';
        tmp[2] = b[i] - 'a';
        tmp[3] = b[j] - 'a';
        sort(tmp, tmp + 4);
        for (int i = 1; i < 4; i++) {
          if (tmp[i] != tmp[i - 1]) break;
          cnt++;
        }
        if (cnt == 2)
          continue;
        else
          ans += 1;
      } else if (kind == 3) {
        if (a[i] == a[j])
          ans += 2;
        else
          ans += 1;
      } else if (kind == 4)
        ans += 2;
    }
    printf("%d\n", ans);
  } else {
    int i, j, ans = 0;
    for (int i = 0; i < n / 2; i++) {
      j = n - i - 1;
      int kind = f(a[i], a[j], b[i], b[j]);
      if (kind == 1)
        continue;
      else if (kind == 2) {
        int cnt = 1;
        int tmp[4];
        tmp[0] = a[i] - 'a';
        tmp[1] = a[j] - 'a';
        tmp[2] = b[i] - 'a';
        tmp[3] = b[j] - 'a';
        sort(tmp, tmp + 4);
        for (int i = 1; i < 4; i++) {
          if (tmp[i] != tmp[i - 1]) break;
          cnt++;
        }
        if (cnt == 2)
          continue;
        else
          ans += 1;
      } else if (kind == 3) {
        if (a[i] == a[j])
          ans += 2;
        else
          ans += 1;
      } else if (kind == 4)
        ans += 2;
    }
    if (a[n / 2] != b[n / 2]) ans++;
    printf("%d\n", ans);
  }
  return 0;
}
