#include <bits/stdc++.h>
using namespace std;
const int inf = 1e9;
const double PI = acos(-1);
const double eps = 1e-6;
const int mod = 1e9 + 7;
const int maxn = 1e5 + 10;
int n;
char a[maxn], b[maxn];
vector<int> q;
int main() {
  cin >> n;
  cin >> a + 1 >> b + 1;
  int ans = 0;
  for (int i = 1; i <= n / 2; i++) {
    q = {a[i], b[i], a[n - i + 1], b[n - i + 1]};
    sort(q.begin(), q.end());
    if (q[0] == q[1] && q[2] == q[3]) continue;
    if (q[0] != q[1] && q[1] != q[2] && q[2] != q[3] && q[3] != q[4]) {
      ans += 2;
      continue;
    }
    if (a[i] == a[n - i + 1]) {
      if (a[i] != b[i] && a[i] != b[n - i + 1]) {
        ans += 2;
      } else
        ans++;
    } else {
      if (b[i] == b[n - i + 1]) {
        ans++;
      } else {
        if (a[i] != b[i] && a[i] != b[n - i + 1]) {
          ans++;
        }
        if (a[n - i + 1] != b[i] && a[n - i + 1] != b[n - i + 1]) {
          ans++;
        }
      }
    }
  }
  if (n & 1) {
    if (a[n / 2 + 1] != b[n / 2 + 1]) ans++;
  }
  cout << ans << endl;
  return 0;
}
