#include <bits/stdc++.h>
using namespace std;
const int N = 1e5 + 10;
string a, b;
int n;
bool check(int idx) {
  string p;
  p += a[idx];
  p += a[n - idx + 1];
  p += b[idx];
  p += b[n - idx + 1];
  sort((p).begin(), (p).end());
  return ((p[0] == p[1]) && (p[2] == p[3]));
}
int main() {
  std::ios::sync_with_stdio(false);
  cin.tie(NULL);
  cout.tie(NULL);
  cin >> n >> a >> b;
  a = '#' + a, b = '#' + b;
  int ans = 0;
  for (int i = 1; i < n / 2 + 1; i++) {
    if (!check(i)) {
      int mn = 2;
      char A = a[i], B = a[n - i + 1];
      for (int k = 0; k < 26; k++) {
        for (int j = 0; j < 26; j++) {
          a[i] = k + 'a';
          a[n - i + 1] = j + 'a';
          if (check(i)) {
            mn = min(mn, (A != k + 'a') + (B != j + 'a'));
          }
        }
      }
      ans += mn;
    }
  }
  if (n & 1 && a[n / 2 + 1] != b[n / 2 + 1]) ++ans;
  cout << ans << endl;
  return 0;
}
