#include <bits/stdc++.h>
using namespace std;
string a, b;
int check(int x, int y) {
  if ((a[x] == b[x] && a[y] == b[y]) || (a[x] == a[y] && b[x] == b[y]) ||
      (a[x] == b[y] && a[y] == b[x]))
    return 0;
  else if (a[x] == b[x] || a[y] == b[y] || a[x] == b[y] || a[y] == b[x] ||
           b[x] == b[y])
    return 1;
  return 2;
}
int main(int argc, char const *argv[]) {
  int n;
  cin >> n;
  cin >> a >> b;
  long long ans = 0;
  for (int i = 0; i < n / 2; i++) {
    ans += check(i, n - i - 1);
  }
  if (n % 2 == 1) {
    if (a[n / 2] != b[n / 2]) ans++;
  }
  cout << ans << endl;
  return 0;
}
