#include <bits/stdc++.h>
using namespace std;
int main() {
  ios_base::sync_with_stdio(0);
  cin.tie(0);
  cout.tie(0);
  long long n;
  string s1, s2;
  cin >> n >> s1 >> s2;
  long long count = 0;
  for (long long i = 0; i < n / 2; i++) {
    long long j = n - 1 - i;
    set<char> a({s1[i], s1[j], s2[i], s2[j]});
    if (s1[i] == s2[i] && s1[j] == s2[j])
      continue;
    else if (s1[i] == s2[i] && s1[j] != s2[j])
      count += 1;
    else if (s1[i] != s2[i] && s1[j] == s2[j])
      count += 1;
    else {
      if (a.size() == 4)
        count += 2;
      else if (a.size() == 3) {
        if (s1[i] == s1[j])
          count += 2;
        else
          count += 1;
      }
    }
  }
  if (n % 2 == 1 and s1[n / 2] != s2[n / 2]) count += 1;
  cout << count;
  return 0;
}
