#include <bits/stdc++.h>
using namespace std;
inline int nxt() {
  int x;
  scanf("%d", &x);
  return x;
}
int per(char a, char b, char c, char d) {
  if (a == b && c == d || a == c && b == d || a == d && c == b)
    return 0;
  else if (a == c || a == d || b == c || b == d || c == d)
    return 1;
  else
    return 2;
}
int main() {
  int n;
  cin >> n;
  int ans = 0, l = 0, r = n - 1;
  string s, w;
  cin >> s >> w;
  while (l <= r) {
    if (l == r) {
      if (s[l] != w[l]) ans++;
      break;
    }
    ans += per(s[l], s[r], w[l], w[r]);
    r--;
    l++;
  }
  cout << ans << "\n";
  return 0;
}
