#include <bits/stdc++.h>
using namespace std;
using ll = long long;
using ii = pair<int, int>;
using pll = pair<ll, ll>;
using vi = vector<int>;
using vl = vector<ll>;
const int INF = 0x3f3f3f3f;
const ll LINF = 0x3f3f3f3f3f3f3f3f;
const double err = 1e-9;
const int mod = 1e9 + 7;
const int N = 1e5 + 10;
int main() {
  ios::sync_with_stdio(0);
  cin.tie(NULL);
  int n;
  cin >> n;
  string a, b;
  cin >> a >> b;
  a = '?' + a;
  b = '?' + b;
  int ans = 0;
  for (int(i) = (1); (i) < (n / 2 + 1); (i)++) {
    vector<int> vec(26, 0);
    vec[a[i] - 'a']++;
    vec[a[n - i + 1] - 'a']++;
    vec[b[i] - 'a']++;
    vec[b[n - i + 1] - 'a']++;
    int hits = 0;
    int inmp = 0;
    for (int(j) = (0); (j) < (26); (j)++) {
      if (vec[j]) hits++;
      if (vec[j] & 1) inmp++;
    }
    if (hits == 4)
      ans += 2;
    else if (hits == 3)
      ans += 1 + (a[i] == a[n - i + 1]);
    else if (hits == 2 and inmp > 0) {
      ans += 1;
    } else if (hits == 1 or (hits == 2 and inmp == 0)) {
    } else {
      assert(false);
    }
  }
  if (n & 1) {
    if (a[n / 2 + 1] != b[n / 2 + 1]) {
      ans++;
    }
  }
  cout << ans << endl;
  return 0;
}
