#include <bits/stdc++.h>
using namespace std;
const int MX = 1 << 22;
const int MOD = 1000000007;
const int64_t mod2 = 1000000007 * 1LL * 1000000007;
const double PI =
    3.141592653589793238462643383279502884197169399375105820974944;
int64_t strtoll(string second) {
  stringstream str(second);
  int64_t number = 0;
  str >> number;
  return number;
}
class Test {
 public:
  int a;
  Test() {
    a = 10;
    std::cout << "Constructor is executed\n";
  }
  ~Test() { std::cout << "Destructor is executed\n"; }
};
class Base {
 public:
  virtual void show() { cout << "In Base \n"; }
};
class Derived : public Base {
 public:
  void show() { cout << "In Derived \n"; }
};
unsigned int onesComplement(unsigned int n) {
  int number_of_bits = floor(log2(n)) + 1;
  return ((1 << number_of_bits) - 1) ^ n;
}
bool vov(char c) {
  if (c == 'a' || c == 'e' || c == 'i' || c == 'o' || c == 'u') return true;
  return false;
}
int solve(int a[26], int i) {
  int ct = 0, one = 0;
  for (int i = 0; i < 26; i++) {
    if (a[i] == 4) {
      return 0;
    } else if (a[i] == 3) {
      return 1;
    } else if (a[i] == 2) {
      ct++;
    } else if (a[i] == 1)
      one++;
  }
  if (ct == 2) return 0;
  if (one == 4) return 2;
}
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(0);
  cout.tie(0);
  int t;
  t = 1;
  for (int tt = 1; tt <= t; tt++) {
    int n;
    cin >> n;
    string a, b;
    cin >> a >> b;
    a = " " + a;
    b = " " + b;
    int ans = 0;
    for (int i = 1; i <= n / 2; i++) {
      int c[26] = {0};
      c[a[i] - 'a']++;
      c[b[i] - 'a']++;
      c[a[n - i + 1] - 'a']++;
      c[b[n - i + 1] - 'a']++;
      bool done = false;
      int ct = 0, one = 0;
      for (int j = 0; j < 26; j++) {
        if (c[j] == 4) {
          done = true;
          break;
        } else if (c[j] == 3) {
          ans += 1;
          done = true;
          break;
        } else if (c[j] == 2) {
          ct++;
        } else if (c[j] == 1)
          one++;
      }
      if (!done) {
        if (one == 4)
          ans += 2;
        else if (ct == 1) {
          ans += 1 + (a[i] == a[n - i + 1]);
        }
      }
    }
    if (n & 1) {
      ans += (a[n / 2 + 1] != b[n / 2 + 1]) ? 1 : 0;
    }
    cout << ans << "\n";
  }
  return 0;
}
