#include <bits/stdc++.h>
using namespace std;
char a[100000 + 5], b[100000 + 5];
int n, ans;
int main() {
  scanf("%d", &n);
  scanf("%s%s", a + 1, b + 1);
  int len1 = strlen(a + 1), len2 = strlen(b + 1);
  for (int i = 1; i <= n / 2; i++) {
    int cont[4], cnt = 0;
    char A[4];
    memset(cont, 0, sizeof(cont));
    A[0] = a[i], A[1] = a[n - i + 1], A[2] = b[i], A[3] = b[n - i + 1];
    for (int q1 = 0; q1 <= 3; q1++)
      for (int q2 = q1 + 1; q2 <= 3; q2++)
        if (A[q1] == A[q2]) cont[q1]++, cont[q2]++;
    for (int p = 0; p <= 3; p++)
      if (cont[p]) cnt++;
    if ((cnt == 3 || cnt == 2) && (A[0] == A[1]))
      ans += 4 - cnt;
    else if (cnt == 3 || cnt == 2)
      ans++;
    if (cnt == 0) ans++, ans++;
  }
  if (n % 2) {
    if (a[(n + 1) / 2] != b[(n + 1) / 2]) ans++;
  }
  printf("%d", ans);
}
