#include <bits/stdc++.h>
using namespace std;
int fun(char a, char b, char c, char d) {
  if ((a == b && c == d) || (a == c && b == d) || (a == d && b == c)) {
    return 0;
  }
  if ((a == c) || (a == d) || (b == c) || (b == d) || (c == d)) {
    return 1;
  }
  return 2;
}
int main() {
  ios::sync_with_stdio(0);
  int n, m, i, j, t, x, y, w, ans = 0;
  cin >> n;
  string str1, str2;
  cin >> str1;
  cin >> str2;
  x = (n + 1) / 2;
  for (i = 0; i < x; i++) {
    y = fun(str1[i], str1[n - i - 1], str2[i], str2[n - i - 1]);
    ans += y;
  }
  if (n % 2) {
    if (str1[x - 1] != str2[x - 1]) {
      ans += 1;
    }
  }
  cout << ans;
  return 0;
}
