#include <bits/stdc++.h>
const long long mod = 1e9 + 7;
using namespace std;
string x, y;
long long n, rs;
map<char, long long> k;
signed main() {
  ios::sync_with_stdio(0);
  cin.tie(0);
  cout.tie(0);
  cin >> n >> x >> y;
  for (long long i = 0; i < n / 2; i++) {
    k[x[i]]++;
    k[x[n - i - 1]]++;
    k[y[i]]++;
    k[y[n - i - 1]]++;
    auto it = k.begin();
    if (k.size() == 4) {
      rs += 2;
      k.clear();
      continue;
    }
    if (k.size() == 3) {
      if (x[i] == x[n - i - 1])
        rs += 2;
      else
        rs += 1;
      k.clear();
      continue;
    }
    if (k.size() == 1) {
      k.clear();
      continue;
    }
    if (k.size() == 2) {
      if (it->second == 3 || it->second == 1) rs++;
      k.clear();
      continue;
    }
  }
  if (n % 2 == 1)
    if (x[n / 2] != y[n / 2]) rs++;
  cout << rs;
}
