#include <bits/stdc++.h>
using namespace std;
const int maxn = 1e5 + 5;
char a[maxn], b[maxn];
int main() {
  int n;
  while (~scanf("%d", &n)) {
    scanf("%s", a);
    scanf("%s", b);
    int ans = 0;
    for (int i = 0; i < n / 2; i++) {
      int letter[26] = {0};
      letter[(int)(a[i] - 'a')]++;
      letter[(int)(b[i] - 'a')]++;
      letter[(int)(a[n - 1 - i] - 'a')]++;
      letter[(int)(b[n - 1 - i] - 'a')]++;
      vector<int> vec;
      for (int j = 0; j < 26; j++) {
        if (letter[j] != 0) vec.push_back(letter[j]);
      }
      if (vec.size() == 4)
        ans += 2;
      else if (vec.size() == 3) {
        if (a[i] == a[n - 1 - i])
          ans += 2;
        else
          ans += 1;
      } else if (vec.size() == 2) {
        if (vec[0] != 2) ans += 1;
      }
    }
    if (n % 2 != 0 && a[n / 2] != b[n / 2]) ans++;
    printf("%d\n", ans);
  }
}
