#include <bits/stdc++.h>
using namespace std;
void __print(long long x) { cerr << x; }
void __print(long x) { cerr << x; }
void __print(unsigned x) { cerr << x; }
void __print(unsigned long x) { cerr << x; }
void __print(unsigned long long x) { cerr << x; }
void __print(float x) { cerr << x; }
void __print(double x) { cerr << x; }
void __print(long double x) { cerr << x; }
void __print(char x) { cerr << '\'' << x << '\''; }
void __print(const char *x) { cerr << '\"' << x << '\"'; }
void __print(const string &x) { cerr << '\"' << x << '\"'; }
void __print(bool x) { cerr << (x ? "true" : "false"); }
template <typename T, typename V>
void __print(const pair<T, V> &x) {
  cerr << '{';
  __print(x.first);
  cerr << ',';
  __print(x.second);
  cerr << '}';
}
template <typename T>
void __print(const T &x) {
  long long f = 0;
  cerr << '{';
  for (auto &i : x) cerr << (f++ ? "," : ""), __print(i);
  cerr << "}";
}
void _print() { cerr << "]\n"; }
template <typename T, typename... V>
void _print(T t, V... v) {
  __print(t);
  if (sizeof...(v)) cerr << ", ";
  _print(v...);
}
const long long N = 2e5 + 4;
const long long mod = 1e9 + 7;
void solve() {
  long long n;
  cin >> n;
  string a, b;
  cin >> a >> b;
  long long ans = 0;
  for (long long i = 0; i < n / 2; i++) {
    if (a[i] == a[n - i - 1] and b[i] == b[n - i - 1]) continue;
    if (a[i] == b[i] and a[n - i - 1] == b[n - i - 1]) continue;
    if (a[i] == b[n - i - 1] and b[i] == a[n - i - 1]) continue;
    bool f = 0, f2 = 0;
    if (b[i] == b[n - i - 1]) {
      ans++;
      continue;
    }
    if (a[i] != b[i] and a[n - i - 1] != b[n - i - 1]) {
      f = 1;
    }
    if (a[i] != b[n - i - 1] and b[i] != a[n - i - 1]) {
      f2 = 1;
    }
    if (f and f2) {
      ans += 2;
    } else {
      ans++;
    }
  }
  if (a[n / 2] != b[n / 2] and n & 1) {
    ans++;
  }
  cout << ans;
}
int32_t main() {
  long long tt;
  tt = 1;
  for (long long t = 1; t <= tt; t++) {
    solve();
  }
}
