#include <bits/stdc++.h>
using namespace std;
const int maxn = 100010;
int n;
char a[maxn], b[maxn];
int cnt(char a1, char a2, char b1, char b2) {
  return (a1 != a2) + (a1 != b1) + (a1 != b2) + (a2 != b1) + (a2 != b2) +
         (b1 != b2);
}
int main() {
  while (scanf("%d", &n) != EOF) {
    scanf("%s%s", a + 1, b + 1);
    int i = 1, j = n;
    int ans = 0;
    while (i < j) {
      int t = cnt(a[i], a[j], b[i], b[j]);
      if (t == 3 || t == 5 && a[i] != a[j]) ans++;
      if (t == 6 || t == 5 && a[i] == a[j]) ans += 2;
      i++, j--;
    }
    if (i == j && a[i] != b[i]) ans++;
    printf("%d\n", ans);
  }
  return 0;
}
