#include <bits/stdc++.h>
using namespace std;
int calc(vector<char> v) {
  if (v[2] == v[3]) {
    if (v[0] != v[1]) {
      return 1;
    }
    return 0;
  } else {
    if (v[0] != v[2] && v[0] != v[3] && v[1] != v[2] && v[1] != v[3]) {
      return 2;
    } else if ((v[0] == v[2] && v[1] == v[3]) ||
               (v[0] == v[3] && v[1] == v[2])) {
      return 0;
    }
    return 1;
  }
}
int main() {
  int n;
  cin >> n;
  string a, b;
  cin >> a >> b;
  int sum = 0;
  for (int i = 0; i < n / 2; ++i) {
    vector<char> c;
    c.push_back(a[i]);
    c.push_back(a[n - 1 - i]);
    c.push_back(b[i]);
    c.push_back(b[n - 1 - i]);
    sum += calc(c);
  }
  if (n % 2 == 1) {
    sum += (a[n / 2] != b[n / 2]);
  }
  cout << sum;
  return 0;
}
