#include <bits/stdc++.h>
using namespace std;
int main() {
  int n, i, j;
  cin >> n;
  string s1, s2;
  cin >> s1 >> s2;
  int ans = 0;
  for (i = 0; i < n / 2; i++) {
    int cnt[26] = {0};
    cnt[s1[i] - 97]++;
    cnt[s1[n - 1 - i] - 97]++;
    cnt[s2[i] - 97]++;
    cnt[s2[n - 1 - i] - 97]++;
    s1[i] -= 97;
    s2[i] -= 97;
    s1[n - 1 - i] -= 97;
    s2[n - 1 - i] -= 97;
    if (cnt[s1[i]] == 4) continue;
    if ((cnt[s1[i]] == 2 && cnt[s1[n - i - 1]] == 2 &&
         cnt[s2[n - i - 1]] == 2 && cnt[s2[i]] == 2))
      continue;
    char c;
    if (s2[i] == s2[n - 1 - i]) {
      if (s1[i] != s1[n - 1 - i]) ans++;
      continue;
    }
    if (s1[i] == s2[i]) {
      if (s1[n - 1 - i] != s2[n - 1 - i]) ans++;
    } else if (s1[i] == s2[n - 1 - i]) {
      if (s1[n - 1 - i] != s2[i]) ans++;
    } else if (s1[n - 1 - i] == s2[i]) {
      if (s1[i] != s2[n - 1 - i]) ans++;
    } else if (s1[n - 1 - i] == s2[n - 1 - i]) {
      if (s1[i] != s2[i]) ans++;
    } else {
      ans += 2;
    }
  }
  if (n % 2 == 1) {
    if (s1[n / 2] != s2[n / 2]) ans++;
  }
  cout << ans;
}
