#include <bits/stdc++.h>
int l, t, s;
char a[100002], b[100002];
int Cnt(int a, int b, int c, int d) {
  return (a != b) + (a != c) + (a != d) + (b != c) + (b != d) + (d != c);
}
int main() {
  scanf("%d%s%s", &l, a + 1, b + 1);
  for (int i = 1; i + i <= l; i++) {
    t = Cnt(a[i], b[i], a[l - i + 1], b[l - i + 1]);
    if (t == 3 || t == 5 && a[i] != a[l - i + 1]) s++;
    if (t == 6 || t == 5 && a[i] == a[l - i + 1]) s += 2;
  }
  printf("%d", s + ((l & 1) && a[l + 1 >> 1] != b[l + 1 >> 1]));
  return 0;
}
