#include <bits/stdc++.h>
using namespace std;
int main() {
  ios_base::sync_with_stdio(0);
  cin.tie(0);
  cout.tie(0);
  long long n;
  string s1, s2;
  cin >> n >> s1 >> s2;
  long long count = 0;
  for (long long i = 0; i < n / 2; i++) {
    char a[4] = {s1[i], s1[n - i - 1], s2[i], s2[n - i - 1]};
    if ((a[0] == a[1] and a[2] == a[3]) || (a[0] == a[3] and a[1] == a[2]) ||
        (a[0] == a[2] and a[1] == a[3]))
      count += 0;
    else if ((a[0] == a[2] and a[1] != a[3]) ||
             (a[0] == a[3] and a[1] != a[2]) ||
             (a[0] != a[2] and a[1] == a[3]) ||
             (a[0] != a[3] and a[1] == a[2]) || (a[0] != a[1] and a[2] == a[3]))
      count += 1;
    else
      count += 2;
  }
  if (n % 2 == 1) count += (s1[n / 2] != s2[n / 2]);
  cout << count;
  return 0;
}
