#include <bits/stdc++.h>
using namespace std;
int count(char a, char b, char c, char d) {
  vector<int> map(26, 0);
  map[a - 'a']++;
  map[b - 'a']++;
  map[c - 'a']++;
  map[d - 'a']++;
  int sum = 0;
  for (int i = 0; i < 26; i++) {
    if (map[i] > 0) sum++;
  }
  return sum;
}
int main() {
  int n;
  cin >> n;
  string a, b;
  cin >> a >> b;
  int i = 0;
  int j = a.size() - 1;
  int pre = 0;
  while (i <= j) {
    if (i == j) {
      if (a[i] != b[i]) pre++;
      i++;
      j--;
    } else {
      int c = count(a[i], a[j], b[i], b[j]);
      if (c == 4)
        pre = pre + 2;
      else if (c == 3) {
        if (a[i] == a[j])
          pre = pre + 2;
        else
          pre = pre + 1;
      } else if (c == 2) {
        if (a[i] == a[j] && a[i] == b[i])
          pre++;
        else if (a[i] == a[j] && a[i] == b[j])
          pre++;
        else if (a[i] == b[i] && a[i] == b[j])
          pre++;
        else if (a[j] == b[i] && a[j] == b[j])
          pre++;
      }
      i++;
      j--;
    }
  }
  cout << pre;
  return 0;
}
