#include <bits/stdc++.h>
using namespace std;
int main() {
  int n;
  char s1[100010], s2[100010];
  while (cin >> n) {
    int ans = 0;
    scanf(" %s %s", s1 + 1, s2 + 1);
    if (n & 1 && s1[n / 2 + 1] != s2[n / 2 + 1]) ans = 1;
    for (int i = 1; i <= n / 2; ++i) {
      int x = i, y = n - i + 1;
      if (s1[x] == s2[x] && s1[y] == s2[y] ||
          s1[x] == s2[y] && s1[y] == s2[x] || s1[x] == s1[y] && s2[x] == s2[y])
        ;
      else if (s1[x] == s2[x] || s2[x] == s2[y] || s2[y] == s1[y] ||
               s1[x] == s2[y] || s1[y] == s2[x])
        ans += 1;
      else
        ans += 2;
    }
    cout << ans << endl;
  }
  return 0;
}
