#include <bits/stdc++.h>
using namespace std;
int n, ans, dd[100005];
string a, b;
int main() {
  ios_base::sync_with_stdio(NULL);
  cin.tie(NULL);
  cout.tie(NULL);
  cin >> n;
  cin >> a >> b;
  a = " " + a;
  b = " " + b;
  for (int i = 1; i <= n / 2; ++i) {
    int a1 = a[i], a2 = a[n - i + 1];
    int b1 = b[i], b2 = b[n - i + 1];
    if (a1 > a2) swap(a1, a2);
    if (b1 > b2) swap(b1, b2);
    if (b1 == b2) {
      ans += (a1 != a2);
      continue;
    }
    if (a1 == b1) {
      ans += (a2 != b2);
      continue;
    }
    if (b1 == a2) {
      ++ans;
      continue;
    }
    ++ans;
    ans += (b2 != a1 && b2 != a2);
  }
  if (n % 2) ans += (a[n / 2 + 1] != b[n / 2 + 1]);
  cout << ans;
}
