#include <bits/stdc++.h>
using namespace std;
int f(string a, string b, int i) {
  int n = a.length();
  string c;
  c += a[i];
  c += a[n - 1 - i];
  c += b[i];
  c += b[n - 1 - i];
  sort(c.begin(), c.end());
  if (c[0] == c[1] && c[2] == c[3]) return 0;
  if (c[0] == c[1] && c[1] == c[2] || c[1] == c[2] && c[2] == c[3]) return 1;
  if (c[0] == c[1] || c[1] == c[2] || c[3] == c[2]) {
    if (a[i] == a[n - 1 - i]) return 2;
    return 1;
  }
  return 2;
}
int main() {
  int n;
  cin >> n;
  string a, b;
  cin >> a >> b;
  int cnt = 0;
  for (int i = 0; i < n / 2; i++) {
    cnt += f(a, b, i);
  }
  if (n % 2 != 0 && a[n / 2] != b[n / 2]) cnt++;
  cout << cnt;
}
