#include <bits/stdc++.h>
using namespace std;
int main() {
  int n;
  string a, b;
  cin >> n >> a >> b;
  int preprocess = 0;
  for (int i = 0; i < (n + 1) / 2; i++) {
    if (a[i] == b[i]) {
      if (b[n - i - 1] != a[n - i - 1]) preprocess++;
    } else if (a[i] == b[n - i - 1]) {
      if (b[i] != a[n - i - 1]) preprocess++;
    } else if (a[n - i - 1] == b[i]) {
      if (a[i] != b[n - i - 1]) preprocess++;
    } else if (a[n - i - 1] == b[n - i - 1]) {
      if (a[i] != b[i]) preprocess++;
    } else if (b[i] == b[n - i - 1]) {
      if (a[i] != a[n - i - 1]) preprocess++;
    } else
      preprocess += 2;
    if (n % 2 and i == n / 2 and a[i] != b[i]) preprocess++;
  }
  cout << preprocess;
}
