#include <bits/stdc++.h>
using namespace std;
int main() {
  int N;
  cin >> N;
  string A, B;
  cin >> A >> B;
  int ans = 0;
  for (int x = 0; x < N - 1 - x; x++) {
    vector<char> v;
    v = {A[x], A[N - 1 - x], B[x], B[N - 1 - x]};
    sort(v.begin(), v.end());
    if (v[0] == v[1] && v[2] == v[3]) continue;
    if ((v[0] == v[1] && v[1] == v[2]) || (v[1] == v[2] && v[2] == v[3])) {
      ans++;
      continue;
    }
    bool flag = true;
    for (int y = 1; y < 4; y++)
      if (v[y] == v[y - 1] && A[x] != A[N - 1 - x]) {
        cerr << v[y] << ' ' << v[y - 1] << endl;
        ans++;
        flag = false;
        break;
      }
    if (flag) ans += 2;
  }
  if (N % 2 && A[N / 2] != B[N / 2]) ans++;
  cout << ans;
  return 0;
}
