#include <bits/stdc++.h>
#pragma GCC optimize("unroll-loops")
using namespace std;
const long long N = 2e5 + 36;
const long long M = 1e3 + 36;
const long long INF = 2e9 + 7;
const long long MOD = 987654323;
const int X[8] = {1, 1, -1, -1, 2, 2, -2, -2};
const int Y[8] = {2, -2, 2, -2, 1, -1, 1, -1};
signed main() {
  ios_base::sync_with_stdio(0);
  cin.tie(0);
  cout.tie(0);
  int n, ans = 0;
  cin >> n;
  string s, t;
  cin >> s >> t;
  for (int i(0); i < (n >> 1); ++i) {
    if (t[i] == t[n - i - 1]) {
      if (s[i] == s[n - i - 1]) {
        continue;
      } else {
        ans += 1;
        continue;
      }
    } else {
      if (s[i] == s[n - i - 1]) {
        if (t[i] == s[i] || t[n - i - 1] == s[i]) {
          ans += 1;
          continue;
        } else {
          ans += 2;
          continue;
        }
      } else {
        if (s[i] != t[i] && s[i] != t[n - i - 1] && s[n - i - 1] != t[i] &&
            s[n - i - 1] != t[n - i - 1]) {
          ans += 2;
          continue;
        }
        if (min(t[i], t[n - i - 1]) == min(s[i], s[n - i - 1]) &&
            max(t[i], t[n - i - 1]) == max(s[i], s[n - i - 1])) {
          continue;
        } else {
          ans += 1;
          continue;
        }
      }
    }
  }
  if (n % 2 == 1) {
    if (s[(n >> 1)] != t[(n >> 1)]) ans++;
  }
  cout << ans << '\n';
  return 0;
}
