#include <bits/stdc++.h>
using namespace std;
priority_queue<pair<int, int>, vector<pair<int, int> >,
               greater<pair<int, int> > >
    pq;
long long int mini(long long int a, long long int b) { return a < b ? a : b; }
long long int maxi(long long int a, long long int b) { return a > b ? a : b; }
long long int gcd(long long int a, long long int b) {
  if (b == 0) return a;
  return gcd(b, a % b);
}
long long int binpow(long long int n, long long int x) {
  long long int ans = 1;
  while (x) {
    if (x & 1) ans *= n;
    n *= n;
    x >>= 1;
  }
  return ans;
}
int main() {
  ios::sync_with_stdio(false);
  cin.tie(0);
  cout.tie(0);
  int n;
  cin >> n;
  string a, b;
  cin >> a >> b;
  int ch = 0;
  int maxval = 1e9;
  for (int i = 0; i < n / 2; ++i) {
    set<int> x;
    x.insert(a[i]);
    x.insert(a[n - i - 1]);
    x.insert(b[i]);
    x.insert(b[n - i - 1]);
    if (x.size() == 4)
      ch += 2;
    else if (x.size() == 3) {
      if (a[i] == a[n - i - 1])
        ch += 2;
      else
        ch += 1;
    } else if (x.size() == 2) {
      if (a[i] == a[n - i - 1] && b[i] == b[n - i - 1])
        continue;
      else if ((a[i] == a[n - i - 1]) || (b[i] == b[n - i - 1]))
        ch++;
    }
  }
  if (n % 2 && a[n / 2] != b[n / 2]) {
    ch++;
  }
  cout << ch << "\n";
  return 0;
}
