#include <bits/stdc++.h>
using namespace std;
const long long int NUM = 2e5 + 5;
int32_t main() {
  ios_base::sync_with_stdio(false);
  cin.tie(0);
  cout.tie(0);
  long long int num_tests = 1;
  while (num_tests-- > 0) {
    long long int n;
    cin >> n;
    string a, b;
    cin >> a >> b;
    long long int ans = 0;
    for (long long int i = 0; i < n / 2; i++) {
      set<char> s;
      s.insert(b[i]);
      s.insert(b[n - 1 - i]);
      if (s.size() == 2) {
        if (a[i] == a[n - 1 - i]) {
          if (s.find(a[i]) == s.end())
            ans += 2;
          else
            ans++;
        } else {
          if (s.find(a[i]) == s.end()) ans++;
          if (s.find(a[n - 1 - i]) == s.end()) ans++;
        }
      }
      if (s.size() == 1) {
        if (a[i] == a[n - 1 - i]) {
        } else
          ans++;
      }
    }
    if (n % 2) {
      if (a[n / 2] != b[n / 2]) {
        ans++;
      }
    }
    cout << ans;
  }
}
